Management of one or more state variables associated with a communication window

ABSTRACT

This disclosure provides systems, methods, and apparatuses, including computer programs encoded on computer storage media, for wireless communication. In one aspect of the disclosure, a user equipment (UE) is configured to manage a state variable (associated with a radio link control (RLC) entity or a packet data convergence protocol (PDCP) entity) that enables the UE to maintain synchronization with a base station during a communication session. For example, a base station may transmit, to the UE, a control PDU or a synchronization PDU that includes a value of a state variable maintained by a base station to enable the UE to update its state variable to maintain synchronization with the base station. Other aspects and features are also claimed and described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for Patent is a continuation of U.S. patentapplication Ser. No. 17/451,618, entitled, “MANAGEMENT OF ONE OR MORESTATE VARIABLES ASSOCIATED WITH A COMMUNICATION WINDOW” (2100384), filedon Oct. 20, 2021, which claims the benefit of U.S. Provisional PatentApplication No. 63/094,862, entitled, “MANAGEMENT OF ONE OR MORE RADIOLINK CONTROL (RLC) STATE VARIABLES,” filed on Oct. 21, 2020,(2100384P1), and U.S. Provisional Patent Application No. 63/109,784,entitled, “MANAGEMENT OF ONE OR MORE STATE VARIABLES ASSOCIATED WITH ACOMMUNICATION WINDOW,” filed on Nov. 4, 2020, (2100384P2), thedisclosure of each of which is hereby incorporated by reference hereinin its entirety as if fully set forth below and for all applicablepurposes.

TECHNICAL FIELD

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to management of one ormore state variables associated with a communication window, such asmanagement of one or more radio link control (RLC) state variables ormanagement of one or more packet data convergence protocol (PDCP) statevariables.

DESCRIPTION OF THE RELATED TECHNOLOGY

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. A wireless multiple-accesscommunications system may include a number of base stations or networkaccess nodes, each simultaneously supporting communication for multiplecommunication devices, which may be otherwise known as user equipment(UE). These systems may be capable of supporting communication withmultiple UEs by sharing the available system resources (such as time,frequency, and power). Examples of such multiple-access systems includefourth generation (4G) systems such as Long Term Evolution (LTE)systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifthgeneration (5G) systems which may be referred to as New Radio (NR)systems. These systems may employ technologies such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal frequency division multipleaccess (OFDMA), or discrete Fourier transform spread orthogonalfrequency division multiplexing (DFT-S-OFDM).

A UE may engage in a unicast or point-to-point (P2P) communicationsession with a base station. To engage in the communication session, theUE configures a radio bearer using a radio link control (RLC) entity andthe RLC entity initializes state variables for RLC acknowledgement mode(AM) window management functionality. During the communication session,the UE, and specifically the RLC entity, may update the state variablesto enable communication. In unicast communication, both transmit andreceive RLC windows are synchronized through an RLC sliding windowmovement procedure without any explicit adjustment command from atransmitting RLC entity to a receiving RLC entity. If the UE attempts aradio link failure recovery procedure or the radio bearer isreconfigured during a handover procedure, the UE re-establishes the RLCentity and re-initializes the state variables to initial values in orderto resume the unicast or point-to-point communication session.

The UE may also engage in a point-to-multiple (P2M) communicationsession, such as for the streaming of a movie or sports game, otherentertainment, or mission critical information. In a P2M communicationsession, the UE may operate in an RLC acknowledged mode (AM) in which abase station uses a single RLC AM transmitter to transmit content to UERLC AM receivers of multiple respective UEs. During the P2Mcommunication session, values of the state variables for UE RLC AMwindow management functionality to maintain a communication window ofthe P2M communication session by the UE may become desynchronized withrespect to the base station. As a result of the desynchronization of thestate variables of the UE and the base station, the UE may discard oneor more received packets of the communication session as being outsideof the communication window maintained by the UE. For example, the UEmay have just performed a handover operation, an RLC communicationwindow may stall, or the UE may join an ongoing multicast session.Because the base station uses the single RLC AM transmitter to transmitcontent associated with a communication session to multiple UEs, thebase station is unable to make an RLC transmit window adjustment tomaintain synchronization on a per-UE basis. Accordingly, a UE RLCreceive window that becomes desynchronized with the base stationtransmit RLC window may result in failure, by the UE, to receive RLCpackets from the base station when these RLC packets fall outside of theUE's RLC receive window.

Additionally, when a multicast bearer (MRB) is configured for acommunication session, a stack may be established that includes multiplelayers, such as one or more of a service data adaptation protocol (SDAP)layer, a packet data convergence protocol (PDCP) layer, an RLC layer, amedia access control (MAC) layer, or a physical (PHY) layer. Forexample, to engage in the communication session, the UE configures aPDCP entity and the PDCP entity initializes state variables for PDCPwindow management functionality. During the communication session,values of the state variables for the UE PDCP window managementfunctionality to maintain a communication window of the P2Mcommunication session by the UE may become desynchronized with respectto the base station. As a result of desynchronization of the statevariables of the UE and the base station, the UE may discard one or morereceived packets of the communication session as being outside of a PDCPcommunication window maintained by the UE based on the state variables.For example, if the UE joins an existing multicast session, the UE mayset one or more state variables associated with the PDU communicationwindow to initial values that may be mismatched or out ofsynchronization with values of state variables of a PDCP entity of thebase station. Accordingly, state variables of the UE used to maintain aUE PDCP communication window that become desynchronized with the statevariables of the base station used to maintain a base station PDCPcommunication window may result in the UE failing to receive PDCP PDUsfrom the base station when these PDCP PDUs fall outside of the UE's PDCPcommunication window.

SUMMARY

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

One innovative aspect of the subject matter described in this disclosurecan be implemented in a method for wireless communication performed by auser equipment (UE). The method includes initializing a set of statevariables to a first set of initial values, respectively. The set ofstate variables are associated with synchronization of a communicationwindow of a communication session. The method further includes receivinga control message including an indication of a second set of currentvalues associated with respective state variables of the set of statevariables. At least one of the current values is different than arespective one of the initial values. The method also includes settingthe set of state variables to the second set of current values tosynchronize the communication window with the communication session, andreceiving or transmitting a packet associated with the communicationsession within the synchronized communication window.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a UE. The UE includes at least oneprocessor and a memory coupled with the at least one processor andstoring processor-readable instructions that, when executed by the atleast one processor, is configured to initialize a set of statevariables to a first set of initial values, respectively. The set ofstate variables are associated with synchronization of a communicationwindow of a communication session. The processor-readable instructions,when executed by the at least one processor, are further configured toreceive a control message including an indication of a second set ofcurrent values associated with respective state variables of the set ofstate variables. At least one of the current values is different than arespective one of the initial values. The processor-readableinstructions, when executed by the at least one processor, are furtherconfigured to set the set of state variables to the second set ofcurrent values to synchronize the communication window with thecommunication session, and receive or transmit a packet associated withthe communication session within the synchronized communication window.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in an apparatus configured for wirelesscommunication. The apparatus includes means for initializing a set ofstate variables to a first set of initial values, respectively. The setof state variables are associated with synchronization of acommunication window of a communication session. The apparatus furtherincludes means for receiving a control message including an indicationof a second set of current values associated with respective statevariables of the set of state variables. At least one of the currentvalues is different than a respective one of the initial values. Theapparatus further includes means for setting the set of state variablesto the second set of current values to synchronize the communicationwindow with the communication session, and means for receiving ortransmitting a packet associated with the communication session withinthe synchronized communication window.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a non-transitory computer-readablemedium storing instructions that, when executed by a processor, causethe processor to perform operations including initializing a set ofstate variables to a first set of initial values, respectively. The setof state variables are associated with synchronization of acommunication window of a communication session. The operations furtherinclude receiving a control message including an indication of a secondset of current values associated with respective state variables of theset of state variables. At least one of the current values is differentthan a respective one of the initial values. The operations furtherinclude setting the set of state variables to the second set of currentvalues to synchronize the communication window with the communicationsession, and receiving or transmitting a packet associated with thecommunication session within the synchronized communication window.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a method for wireless communicationperformed by a base station. The method includes generating a controlmessage including an indication of a set of values of a set of statevariables associated with a communication window of a communicationsession. The set of values enable synchronization of the communicationwindow and are different from a set of initial values of the set ofstate variables. The method further includes transmitting the controlmessage to a UE.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a base station. The base stationincludes at least one processor and a memory coupled with the at leastone processor and storing processor-readable code that, when executed bythe at least one processor, is configured to generate a control messageincluding an indication of a set of values of a set of state variablesassociated with a communication window of a communication session. Theset of values enable synchronization of the communication window and aredifferent from a set of initial values of the set of state variables.The processor-readable code, when executed by the at least oneprocessor, is further configured to initiate transmission of the controlmessage to a UE.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in an apparatus configured for wirelesscommunication. The apparatus includes means for generating a controlmessage including an indication of a set of values of a set of statevariables associated with a communication window of a communicationsession. The set of values enable synchronization of the communicationwindow and are different from a set of initial values of the set ofstate variables. The apparatus further includes means for transmittingthe control message to a UE.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a non-transitory computer-readablemedium storing instructions that, when executed by a processor, causethe processor to perform operations including generating a controlmessage including an indication of a set of values of a set of statevariables associated with a communication window of a communicationsession. The set of values enable synchronization of the communicationwindow and are different from a set of initial values of the set ofstate variables. The operations further include initiating transmissionof the control message to a UE.

Other aspects, features, and implementations of the present disclosurewill become apparent to a person having ordinary skill in the art, uponreviewing the following description of specific, example implementationsof the present disclosure in conjunction with the accompanying figures.While features of the present disclosure may be described relative toparticular implementations and figures below, all implementations of thepresent disclosure can include one or more of the advantageous featuresdescribed herein. In other words, while one or more implementations maybe described as having particular advantageous features, one or more ofsuch features may also be used in accordance with the variousimplementations of the disclosure described herein. In similar fashion,while example implementations may be described below as device, system,or method implementations, such example implementations can beimplemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a second label or by adash and a second label that distinguishes among the similar components.If just the first reference label is used in the specification, thedescription is applicable to any one of the similar components havingthe same first reference label irrespective of the second referencelabel.

FIG. 1 is a block diagram illustrating details of an example wirelesscommunication system according to one or more aspects.

FIG. 2 is a block diagram illustrating examples of a base station and auser equipment (UE) according to one or more aspects.

FIG. 3 is a block diagram illustrating an example wireless communicationsystem that supports management of a state variable according to one ormore aspects.

FIG. 4 is a block diagram illustrating another example wirelesscommunication system that supports management of a state variableaccording to one or more aspects.

FIG. 5 is a flow diagram illustrating an example process that supportsmanagement of a state variable according to one or more aspects.

FIG. 6 is a block diagram of an example UE that supports management of astate variable according to one or more aspects.

FIG. 7 is a flow diagram illustrating an example process that supportsmanagement of a state variable according to one or more aspects.

FIG. 8 is a block diagram of an example base station that supportsmanagement of a state variable according to one or more aspects.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and are not to be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art may appreciate that the scope ofthe disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any quantity of theaspects set forth herein. In addition, the scope of the disclosure isintended to cover such an apparatus or method which is practiced usingother structure, functionality, or structure and functionality inaddition to or other than the various aspects of the disclosure setforth herein. Any aspect of the disclosure disclosed herein may beembodied by one or more elements of a claim.

Various aspects of the present disclosure relate to techniques thatenable a user equipment (UE) to maintain synchronization of one or morestate variables of the UE with one or more respective state variables ofa network entity (such as a base station) during a communicationsession. The UE may use the state variables to maintain a communicationwindow in synchronization with respect to a corresponding communicationwindow maintained by the network entity based on the respective statevariable of the network entity. For example, the state variables may beassociated with a radio link control (RLC) entity acknowledged mode (AM)window functionality of the UE, an RLC entity unacknowledged mode (UM)window functionality of the UE, or a packet data convergence protocol(PDCP) entity window functionality. The communication may be, in variousexamples, a unicast communication session, a multicast communicationsession, or a broadcast communication session with the base station. Insome aspects, the UE may establish an entity, such as the RLC entity orthe PDCP entity, to join the communication session and may initialize aset of state variables associated with a communication window, such as asliding window. For example, the set of state variables may beinitialized to a set of initial values. After the UE successfullyconfigures the entity, the base station may transmit a control message,such as a control protocol data unit (PDU), to the UE that includes aset of current values of the respective state variables maintained bythe base station to enable the UE to update its state variables based onthe set of current values. For example, the UE may update its statevariables to be the same as the set of current values. By updating itsstate variables based on the set of current values, the UE is able tosynchronize its communication window of the communication session withthe base station. In some implementations, the control PDU may be sentwithout an assigned RLC sequence number (SN).

In some aspects, during the communication session, the UE may perform ahandover operation from a current cell associated with the base stationto a target cell associated with the base station or a different basestation, and may re-establish the entity as part of the handoveroperation. Based on successful completion of the handover operation, thebase station associated with the target cell may transmit a control PDU(without an assigned RLC SN) to the UE to enable the UE to update itsstate variables and maintain synchronization between the UE and the basestation associated with the target cell.

In some aspects, the base station may transmit one or moresynchronization (synch) PDUs to the UE during the communication session.For example, the base station may transmit the synchronization PDUsperiodically. In some examples, each synchronization PDU may include orbe transmitted with an RLC SN and may include one or more current valuesof one or more of the state variables maintained by the base station toenable the UE to determine whether or not to update its respective statevariables to synchronize the communication window of the communicationsession with the base station. Additionally, if the UE does not receive,using the communication window, a packet associated with the entitywithin a time period, the UE may determine that the communication windowis “stalled” and the UE may subsequently re-establish the entity, whichmay, in turn, cause an interruption to the communication session by theUE.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. By providing a control messages that includes thecurrent value of a state variable maintained by the base station to theUE, the UE may update its state variables to manage its communicationwindow to maintain synchronization with the base station and experiencefewer interruptions during the communication session, thereby improvinguser experience. In some implementations, the control may be sentwithout an assigned RLC SN, which may reduce communication overhead.Additionally, in implementations where the base station transmits one ormore synchronization PDU, the one or more synchronization PDUs mayenable the UE to maintain synchronization of the communication windowwith the base station and avoid the communication window becomingstalled.

In various implementations, the techniques, procedures and apparatusdisclosed herein may be used for wireless communication networks such ascode division multiple access (CDMA) networks, time division multipleaccess (TDMA) networks, frequency division multiple access (FDMA)networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA(SC-FDMA) networks, LTE networks, GSM networks, 5th Generation (5G) ornew radio (NR) networks (sometimes referred to as “5G NR” networks,systems, or devices), as well as other communications networks. Asdescribed herein, the terms “networks” and “systems” may be usedinterchangeably.

A CDMA network may implement a radio technology such as universalterrestrial radio access (UTRA), cdma2000, and the like. UTRA includeswideband-CDMA (W-CDMA) and low chip rate (LCR). CDMA2000 covers IS-2000,IS-95, and IS-856 standards.

A TDMA network may implement a radio technology such as Global Systemfor Mobile Communications (GSM). 3GPP defines standards for the GSM EDGE(enhanced data rates for GSM evolution) radio access network (RAN), alsodenoted as GERAN. GERAN is the radio component of GSM or GSM EDGE,together with the network that joins the base stations (for example, theAter and Abis interfaces, among other examples) and the base stationcontrollers (for example, A interfaces, among other examples). The radioaccess network represents a component of a GSM network, through whichphone calls and packet data are routed from and to the public switchedtelephone network (PSTN) and Internet to and from subscriber handsets,also known as user terminals or user equipments (UEs). A mobile phoneoperator's network may include one or more GERANs, which may be coupledwith UTRANs in the case of a UMTS or GSM network. Additionally, anoperator network may include one or more LTE networks, or one or moreother networks. The various different network types may use differentradio access technologies (RATs) and radio access networks (RANs).

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and thelike. UTRA, E-UTRA, and GSM are part of universal mobiletelecommunication system (UMTS). In particular, long term evolution(LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS andLTE are described in documents provided from an organization named the“3rd Generation Partnership Project” (3GPP), and cdma2000 is describedin documents from an organization named “3rd Generation PartnershipProject 2” (3GPP2). These various radio technologies and standards areknown or are being developed. For example, the 3GPP is a collaborationbetween groups of telecommunications associations that aims to define aglobally applicable third generation (3G) mobile phone specification.3GPP long term evolution (LTE) is a 3GPP project aimed at improving theuniversal mobile telecommunications system (UMTS) mobile phone standard.The 3GPP may define specifications for the next generation of mobilenetworks, mobile systems, and mobile devices. The present disclosure maydescribe certain aspects with reference to LTE, 4G, 5G, or NRtechnologies; however, the description is not intended to be limited toa specific technology or application, and one or more aspects describedwith reference to one technology may be understood to be applicable toanother technology. Indeed, one or more aspects the present disclosureare related to shared access to wireless spectrum between networks usingdifferent radio access technologies or radio air interfaces.

5G networks contemplate diverse deployments, diverse spectrum, anddiverse services and devices that may be implemented using an OFDM-basedunified, air interface. To achieve these goals, further enhancements toLTE and LTE-A are considered in addition to development of the new radiotechnology for 5G NR networks. The 5G NR will be capable of scaling toprovide coverage (1) to a massive Internet of things (IoTs) with anultra-high density (such as ˜1M nodes per km²), ultra-low complexity(such as ˜10 s of bits per sec), ultra-low energy (such as ˜10+ years ofbattery life), and deep coverage with the capability to reachchallenging locations; (2) including mission-critical control withstrong security to safeguard sensitive personal, financial, orclassified information, ultra-high reliability (such as ˜99.9999%reliability), ultra-low latency (such as ˜1 millisecond (ms)), and userswith wide ranges of mobility or lack thereof; and (3) with enhancedmobile broadband including extreme high capacity (such as ˜10 Tbps perkm2), extreme data rates (such as multi-Gbps rate, 100+ Mbps userexperienced rates), and deep awareness with advanced discovery andoptimizations.

Devices, networks, and systems may be configured to communicate via oneor more portions of the electromagnetic spectrum. The electromagneticspectrum is often subdivided, based on frequency or wavelength, intovarious classes, bands, channels, etc. In 5G NR two initial operatingbands have been identified as frequency range designations FR1 (410MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). The frequencies between FR1and FR2 are often referred to as mid-band frequencies. Although aportion of FR1 is greater than 6 GHz, FR1 is often referred to(interchangeably) as a “sub-6 GHz” band in various documents andarticles. A similar nomenclature issue sometimes occurs with regard toFR2, which is often referred to (interchangeably) as a “millimeter wave”(mmWave) band in documents and articles, despite being different fromthe extremely high frequency (EHF) band (30 GHz-300 GHz) which isidentified by the International Telecommunications Union (ITU) as a“mmWave” band. With the above aspects in mind, unless specificallystated otherwise, it should be understood that the term “sub-6 GHz” orthe like if used herein may broadly represent frequencies that may beless than 6 GHz, may be within FR1, or may include mid-band frequencies.Further, unless specifically stated otherwise, it should be understoodthat the term “mmWave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2, ormay be within the EHF band.

5G NR devices, networks, and systems may be implemented to use optimizedOFDM-based waveform features. These features may include scalablenumerology and transmission time intervals (TTIs); a common, flexibleframework to efficiently multiplex services and features with a dynamic,low-latency time division duplex (TDD) or frequency division duplex(FDD) design; and advanced wireless technologies, such as massivemultiple input, multiple output (MIMO), robust millimeter wave (mmWave)transmissions, advanced channel coding, and device-centric mobility.Scalability of the numerology in 5G NR, with scaling of subcarrierspacing, may efficiently address operating diverse services acrossdiverse spectrum and diverse deployments. For example, in variousoutdoor and macro coverage deployments of less than 3 GHz FDD or TDDimplementations, subcarrier spacing may occur with 15 kHz, for exampleover 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoorand small cell coverage deployments of TDD greater than 3 GHz,subcarrier spacing may occur with 30 kHz over 80 or 100 MHz bandwidth.For other various indoor wideband implementations, using a TDD over theunlicensed portion of the 5 GHz band, the subcarrier spacing may occurwith 60 kHz over a 160 MHz bandwidth. Finally, for various deploymentstransmitting with mmWave components at a TDD of 28 GHz, subcarrierspacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of 5G NR facilitates scalable TTI for diverselatency and quality of service (QoS) requirements. For example, shorterTTI may be used for low latency and high reliability, while longer TTImay be used for higher spectral efficiency. The efficient multiplexingof long and short TTIs to allow transmissions to start on symbolboundaries. 5G NR also contemplates a self-contained integrated subframedesign with uplink or downlink scheduling information, data, andacknowledgement in the same subframe. The self-contained integratedsubframe supports communications in unlicensed or contention-basedshared spectrum, adaptive uplink or downlink that may be flexiblyconfigured on a per-cell basis to dynamically switch between uplink anddownlink to meet the current traffic needs.

For clarity, certain aspects of the apparatus and techniques may bedescribed below with reference to example 5G NR implementations or in a5G-centric way, and 5G terminology may be used as illustrative examplesin portions of the description below; however, the description is notintended to be limited to 5G applications.

Moreover, it should be understood that, in operation, wirelesscommunication networks adapted according to the concepts herein mayoperate with any combination of licensed or unlicensed spectrumdepending on loading and availability. Accordingly, it will be apparentto a person having ordinary skill in the art that the systems, apparatusand methods described herein may be applied to other communicationssystems and applications than the particular examples provided.

FIG. 1 is a block diagram illustrating details of an example wirelesscommunication system. The wireless communication system may includewireless network 100. The wireless network 100 may, for example, includea 5G wireless network. As appreciated by those skilled in the art,components appearing in FIG. 1 are likely to have related counterpartsin other network arrangements including, for example, cellular-stylenetwork arrangements and non-cellular-style-network arrangements, suchas device-to-device, peer-to-peer or ad hoc network arrangements, amongother examples.

The wireless network 100 illustrated in FIG. 1 includes a number of basestations 105 and other network entities. A base station may be a stationthat communicates with the UEs and may be referred to as an evolved nodeB (eNB), a next generation eNB (gNB), an access point, and the like.Each base station 105 may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to thisparticular geographic coverage area of a base station or a base stationsubsystem serving the coverage area, depending on the context in whichthe term is used. In implementations of the wireless network 100 herein,the base stations 105 may be associated with a same operator ordifferent operators, such as the wireless network 100 may include aplurality of operator wireless networks. Additionally, inimplementations of the wireless network 100 herein, the base stations105 may provide wireless communications using one or more of the samefrequencies, such as one or more frequency bands in licensed spectrum,unlicensed spectrum, or a combination thereof, as a neighboring cell. Insome examples, an individual base station 105 or UE 115 may be operatedby more than one network operating entity. In some other examples, eachbase station 105 and UE 115 may be operated by a single networkoperating entity.

A base station may provide communication coverage for a macro cell or asmall cell, such as a pico cell or a femto cell, or other types of cell.A macro cell generally covers a relatively large geographic area, suchas several kilometers in radius, and may allow unrestricted access byUEs with service subscriptions with the network provider. A small cell,such as a pico cell, would generally cover a relatively smallergeographic area and may allow unrestricted access by UEs with servicesubscriptions with the network provider. A small cell, such as a femtocell, would also generally cover a relatively small geographic area,such as a home, and, in addition to unrestricted access, may providerestricted access by UEs having an association with the femto cell, suchas UEs in a closed subscriber group (CSG), UEs for users in the home,and the like. A base station for a macro cell may be referred to as amacro base station. A base station for a small cell may be referred toas a small cell base station, a pico base station, a femto base stationor a home base station. In the example shown in FIG. 1 , base stations105 d and 105 e are regular macro base stations, while base stations 105a-105 c are macro base stations enabled with one of 3 dimension (3D),full dimension (FD), or massive MIMO. Base stations 105 a-105 c takeadvantage of their higher dimension MIMO capabilities to exploit 3Dbeamforming in both elevation and azimuth beamforming to increasecoverage and capacity. Base station 105 f is a small cell base stationwhich may be a home node or portable access point. A base station maysupport one or multiple cells, such as two cells, three cells, fourcells, and the like.

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the base stations may have similarframe timing, and transmissions from different base stations may beapproximately aligned in time. For asynchronous operation, the basestations may have different frame timing, and transmissions fromdifferent base stations may not be aligned in time. In some scenarios,networks may be enabled or configured to handle dynamic switchingbetween synchronous or asynchronous operations.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE may be stationary or mobile. It should be appreciated that, althougha mobile apparatus is commonly referred to as user equipment (UE) instandards and specifications promulgated by the 3GPP, such apparatus mayadditionally or otherwise be referred to by those skilled in the art asa mobile station (MS), a subscriber station, a mobile unit, a subscriberunit, a wireless unit, a remote unit, a mobile device, a wirelessdevice, a wireless communications device, a remote device, a mobilesubscriber station, an access terminal (AT), a mobile terminal, awireless terminal, a remote terminal, a handset, a terminal, a useragent, a mobile client, a client, or some other suitable terminology.Within the present document, a “mobile” apparatus or UE need notnecessarily have a capability to move, and may be stationary. Somenon-limiting examples of a mobile apparatus, such as may includeimplementations of one or more of the UEs 115, include a mobile, acellular (cell) phone, a smart phone, a session initiation protocol(SIP) phone, a wireless local loop (WLL) station, a laptop, a personalcomputer (PC), a notebook, a netbook, a smart book, a tablet, and apersonal digital assistant (PDA). A mobile apparatus may additionally bean “Internet of things” (IoT) or “Internet of everything” (IoE) devicesuch as an automotive or other transportation vehicle, a satelliteradio, a global positioning system (GPS) device, a global navigationsatellite system (GNSS) device, a logistics controller, a drone, amulti-copter, a quad-copter, a smart energy or security device, a solarpanel or solar array, municipal lighting, water, or otherinfrastructure; industrial automation and enterprise devices; consumerand wearable devices, such as eyewear, a wearable camera, a smart watch,a health or fitness tracker, a mammal implantable device, a gesturetracking device, a medical device, a digital audio player (such as MP3player), a camera or a game console, among other examples; and digitalhome or smart home devices such as a home audio, video, and multimediadevice, an appliance, a sensor, a vending machine, intelligent lighting,a home security system, or a smart meter, among other examples. In oneaspect, a UE may be a device that includes a Universal IntegratedCircuit Card (UICC). In another aspect, a UE may be a device that doesnot include a UICC. In some aspects, UEs that do not include UICCs maybe referred to as IoE devices. The UEs 115 a-115 d of the implementationillustrated in FIG. 1 are examples of mobile smart phone-type devicesaccessing the wireless network 100. A UE may be a machine specificallyconfigured for connected communication, including machine typecommunication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) andthe like. The UEs 115 e-115 k illustrated in FIG. 1 are examples ofvarious machines configured for communication that access 5G network100.

A mobile apparatus, such as the UEs 115, may be able to communicate withany type of the base stations, whether macro base stations, pico basestations, femto base stations, relays, and the like. In FIG. 1 , acommunication link (represented as a lightning bolt) indicates wirelesstransmissions between a UE and a serving base station, which is a basestation designated to serve the UE on the downlink or uplink, or desiredtransmission between base stations, and backhaul transmissions betweenbase stations. Backhaul communication between base stations of thewireless network 100 may occur using wired or wireless communicationlinks.

In operation at the 5G network 100, the base stations 105 a-105 c servethe UEs 115 a and 115 b using 3D beamforming and coordinated spatialtechniques, such as coordinated multipoint (CoMP) or multi-connectivity.Macro base station 105 d performs backhaul communications with the basestations 105 a-105 c, as well as small cell, the base station 105 f.Macro base station 105 d also transmits multicast services which aresubscribed to and received by the UEs 115 c and 115 d. Such multicastservices may include mobile television or stream video, or may includeother services for providing community information, such as weatheremergencies or alerts, such as Amber alerts or gray alerts.

The wireless network 100 of implementations supports mission criticalcommunications with ultra-reliable and redundant links for missioncritical devices, such the UE 115 e, which is a drone. Redundantcommunication links with the UE 115 e include from the macro basestations 105 d and 105 e, as well as small cell base station 105 f.Other machine type devices, such as UE 115 f (thermometer), the UE 115 g(smart meter), and the UE 115 h (wearable device) may communicatethrough the wireless network 100 either directly with base stations,such as the small cell base station 105 f, and the macro base station105 e, or in multi-hop configurations by communicating with another userdevice which relays its information to the network, such as the UE 115 fcommunicating temperature measurement information to the smart meter,the UE 115 g, which is then reported to the network through the smallcell base station 105 f. The 5G network 100 may provide additionalnetwork efficiency through dynamic, low-latency TDD or FDDcommunications, such as in a vehicle-to-vehicle (V2V) mesh networkbetween the UEs 115 i-115 k communicating with the macro base station105 e.

FIG. 2 is a block diagram conceptually illustrating an example design ofa base station 105 and a UE 115. The base station 105 and the UE 115 maybe one of the base stations and one of the UEs in FIG. 1 . For arestricted association scenario (as mentioned above), the base station105 may be the small cell base station 105 f in FIG. 1 , and the UE 115may be the UE 115 c or 115 d operating in a service area of the basestation 105 f, which in order to access the small cell base station 105f, would be included in a list of accessible UEs for the small cell basestation 105 f. Additionally, the base station 105 may be a base stationof some other type. As shown in FIG. 2 , the base station 105 may beequipped with antennas 234 a through 234 t, and the UE 115 may beequipped with antennas 252 a through 252 r for facilitating wirelesscommunications.

At the base station 105, a transmit processor 220 may receive data froma data source 212 and control information from a controller 240. Thecontrol information may be for the physical broadcast channel (PBCH),physical control format indicator channel (PCFICH), physical hybrid-ARQ(automatic repeat request) indicator channel (PHICH), physical downlinkcontrol channel (PDCCH), enhanced physical downlink control channel(EPDCCH), or MTC physical downlink control channel (MPDCCH), among otherexamples. The data may be for the PDSCH, among other examples. Thetransmit processor 220 may process, such as encode and symbol map, thedata and control information to obtain data symbols and control symbols,respectively. Additionally, the transmit processor 220 may generatereference symbols, such as for the primary synchronization signal (PSS)and secondary synchronization signal (SSS), and cell-specific referencesignal. Transmit (TX) multiple-input multiple-output (MIMO) processor230 may perform spatial processing on the data symbols, the controlsymbols, or the reference symbols, if applicable, and may provide outputsymbol streams to modulators (MODs) 232 a through 232 t. For example,spatial processing performed on the data symbols, the control symbols,or the reference symbols may include precoding. Each modulator 232 mayprocess a respective output symbol stream, such as for OFDM, among otherexamples, to obtain an output sample stream. Each modulator 232 mayadditionally or alternatively process the output sample stream to obtaina downlink signal. For example, to process the output sample stream,each modulator 232 may convert to analog, amplify, filter, and upconvertthe output sample stream to obtain the downlink signal. Downlink signalsfrom modulators 232 a through 232 t may be transmitted via the antennas234 a through 234 t, respectively.

At the UE 115, the antennas 252 a through 252 r may receive the downlinksignals from the base station 105 and may provide received signals tothe demodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition a respective received signal to obtaininput samples. For example, to condition the respective received signal,each demodulator 254 may filter, amplify, downconvert, and digitize therespective received signal to obtain the input samples. Each demodulator254 may further process the input samples, such as for OFDM, among otherexamples, to obtain received symbols. MIMO detector 256 may obtainreceived symbols from demodulators 254 a through 254 r, perform MIMOdetection on the received symbols if applicable, and provide detectedsymbols. Receive processor 258 may process the detected symbols, providedecoded data for the UE 115 to a data sink 260, and provide decodedcontrol information to a controller 280. For example, to process thedetected symbols, the receive processor 258 may demodulate,deinterleave, and decode the detected symbols.

On the uplink, at the UE 115, a transmit processor 264 may receive andprocess data (such as for the physical uplink shared channel (PUSCH))from a data source 262 and control information (such as for the physicaluplink control channel (PUCCH)) from the controller 280. Additionally,the transmit processor 264 may generate reference symbols for areference signal. The symbols from the transmit processor 264 may beprecoded by TX MIMO processor 266 if applicable, further processed bythe modulators 254 a through 254 r (such as for SC-FDM, among otherexamples), and transmitted to the base station 105. At base station 105,the uplink signals from the UE 115 may be received by antennas 234,processed by demodulators 232, detected by MIMO detector 236 ifapplicable, and further processed by receive processor 238 to obtaindecoded data and control information sent by the UE 115. The receiveprocessor 238 may provide the decoded data to data sink 239 and thedecoded control information to the controller 240.

The controllers 240 and 280 may direct the operation at the base station105 and the UE 115, respectively. The controller 240 or other processorsand modules at the base station 105 or the controller 280 or otherprocessors and modules at the UE 115 may perform or direct the executionof various processes for the techniques described herein, such as toperform or direct the execution illustrated in FIGS. 5 and 7 , or otherprocesses for the techniques described herein. The memories 242 and 282may store data and program codes for the base station 105 and The UE115, respectively. Scheduler 244 may schedule UEs for data transmissionon the downlink or uplink.

In some cases, the UE 115 and the base station 105 may operate in ashared radio frequency spectrum band, which may include licensed orunlicensed, such as contention-based, frequency spectrum. In anunlicensed frequency portion of the shared radio frequency spectrumband, the UEs 115 or the base stations 105 may traditionally perform amedium-sensing procedure to contend for access to the frequencyspectrum. For example, the UE 115 or base station 105 may perform alisten-before-talk or listen-before-transmitting (LBT) procedure such asa clear channel assessment (CCA) prior to communicating in order todetermine whether the shared channel is available. A CCA may include anenergy detection procedure to determine whether there are any otheractive transmissions. For example, a device may infer that a change in areceived signal strength indicator (RSSI) of a power meter indicatesthat a channel is occupied. Specifically, signal power that isconcentrated in a certain bandwidth and exceeds a predetermined noisefloor may indicate another wireless transmitter. In someimplementations, a CCA may include detection of specific sequences thatindicate use of the channel. For example, another device may transmit aspecific preamble prior to transmitting a data sequence. In some cases,an LBT procedure may include a wireless node adjusting its own back offwindow based on the amount of energy detected on a channel or theacknowledge or negative-acknowledge (ACK or NACK) feedback for its owntransmitted packets as a proxy for collisions.

Various aspects of the present disclosure relate to techniques thatenable a user equipment (UE) to maintain synchronization of a statevariable of the UE with a state variable of a network (base station)during a communication session. For example, the state variable may beassociated with a radio link control (RLC) entity acknowledged mode (AM)window state variable of the UE or a packet data convergence protocol(PDCP) entity window state variable. In some aspects, the UE mayestablish an entity, such as the RLC entity or the PDCP entity, to jointhe communication session, such as a unicast communication session, amulticast communication session, or a broadcast communication sessionwith the base station. Additionally, the UE may initialize one or morestate variables associated with a communication window, such as asliding window. Based on the UE successfully configuring the entity or amode of the RLC entity, such as a UM mode or an AM mode, the basestation may transmit a control protocol data unit (PDU) to the UE thatincludes a set of one or more current values of the one or more statevariables (maintained by the base station) to enable the UE to updateits state variables to synchronize the communication window of thecommunication session with the base station. In some implementations,the control PDU may be sent without an RLC sequence number (SN)assigned.

In some aspects, during the communication session, the UE may perform ahandover operation to a target cell associated with the base station andmay re-establish the entity. Based on completion of the handoveroperation, the base station associated with the target cell may transmita control PDU (without an RLC SN assigned) to the UE to enable the UE tomanage its state variables and maintain synchronization between theentity of the UE and an entity of the base station associated with thetarget cell.

In some aspects, the base station may transmit one or moresynchronization (synch) PDUs to the UE during the communication session.For example, the base station may periodically transmit synchronizationPDUs to the UE. In some implementations, each synchronization PDU mayinclude or be transmitted with an RLC SN and may include one or morecurrent values of the one or more state variables (maintained by thebase station) to enable the UE to determine whether or not to update itsstate variables to synchronize a communication window of thecommunication session with the base station to avoid dropping receivedpackets. Additionally, if the UE does not receive a valid packetassociated with the entity, such as the RLC entity or the PDCP entity,within a time period, the communication window is determined to be“stalled” and the UE re-establishes the entity, which may cause aninterruption to receipt of the communication session by the UE.According, the one or more synchronization PDUs may enable the UE tomaintain synchronization of the communication window with the basestation and avoid the communication window becoming stalled.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. In some aspects, the present disclosure presentstechniques for management of one or more state variables, such as statevariables associated with an RLC AM entity, and RLC UM entity, or a PDCPentity. For example, a base station may maintain various state variablesand provide a value of each of one or more of the state variables to aUE to enable the UE to maintain synchronization with the base station.For example, the value of a state variable may enable the UE tosynchronize with the base station based on the UE establishing the RLCAM entity or the PDCP entity and joining a communication session, orbased on the UE performing a handover operation and re-establishing theRLC AM entity, the RLC UM entity, or the PDCP entity. In addition toproviding the value of the state variable based on the UE joining thecommunication session or performing a handover operation, the basestation may also provide the value of the state variable at one or moreother times during the communication session. By providing the value ofa state variable maintained by the base station to the UE, the UE maymanage synchronization with the base station and experience fewerinterruptions during the communication session, thereby improving userexperience.

FIG. 3 is a block diagram of an example wireless communications system300 that supports management of a state variable according to one ormore aspects. In some examples, the wireless communications system 300may implement aspects of the wireless network 100. The wirelesscommunications system 300 includes the UE 115, the base station 105, abase station 360, and a content provider 352. Although one UE 115 andtwo base station 105 and 360 are illustrated, in some otherimplementations, the wireless communications system 300 may generallyinclude multiple UEs 115, and may include one base station or more thantwo base stations. In some implementations, the base station 105 may beassociated with a first cell and the base station 360 may be associatedwith a second cell. In some other implementations, the base station 105is associated with a first cell and a second cell.

The UE 115 can include a variety of components (such as structural,hardware components) used for carrying out one or more functionsdescribed herein. For example, these components can include one or moreprocessors 302 (hereinafter referred to collectively as “the processor302”), one or more memory devices 304 (hereinafter referred tocollectively as “the memory 304”), one or more transmitters 316(hereinafter referred to collectively as “the transmitter 316”), one ormore receivers 318 (hereinafter referred to collectively as “thereceiver 318”), and an RLC entity 320. The processor 302 may beconfigured to execute instructions stored in the memory 304 to performthe operations described herein. In some implementations, the processor302 includes or corresponds to one or more of the receive processor 258,the transmit processor 264, and the controller 280, and the memory 304includes or corresponds to the memory 282.

The memory 304 includes or is configured to store one or more statevariables 306 (hereinafter referred to collectively as “the statevariable 306”), one or more initial values 308 (hereinafter referred tocollectively as “the initial value 308”). The state variable 306 may beassociated with operation of or communication via the RLC entity 320,such as a communication window. For example, the state variable 306 mayinclude a window size, a lower edge value, an upper edge value, or acombination thereof.

The state variable 306 may include or correspond to a data transfer,such as a UM data transfer or an AM data transfer. For example, the UE115 may maintain a current value of the state variable 306 during acommunication session. In some implementations, the UE 115 may initiatea communication session and set the state variable 306 to the initialvalue 308. For example, the UE 115 may set the state variable 306 to theinitial value 308 based on establishment or re-establishment of the RLCentity 320. Additionally, or alternative, during the communicationsession, the UE 115 may adjust the value of the state variable 306 asdescribe further herein.

The state variable 306 may be set to a non-negative integer. As anillustrative, non-limiting example, the state variable 306 is describedherein with reference to an AM data transfer. Although described hereinwith reference to the AM data transfer, it is noted that suchdescription is not intended to be limiting and, in some implementations,the state variables 306 may be associated with a UM data transfer. Inassociation with the AM data transfer, the state variables 306 may havea value from 0 to 4095 for a 12 bit SN or from 0 to 262143 for an 18 bitSN. The UE 115 may perform one or more arithmetic operations on thestate variable 306 related to the AM data transfer based on an AMmodulus, such as. final value=[value from arithmetic operation] modulo4096 for 12 bit SN and 262144 for 18 bit SN. It is noted that whenperforming arithmetic comparisons of the state variable 306 or a SNvalue, a modulus base may be used.

A TX_Next_Ack and an RX_Next may be assumed as the modulus base at thetransmitting side and receiving side of the RLC entity 320 (such as anAM RLC entity), respectively. This modulus base may be subtracted fromall the values involved, and then an absolute comparison may beperformed. To illustrate, RX_Next<=SN<RX_Next+AM_Window_Size may beevaluated as [RX_Next−RX_Next] modulo 2^([sn-FieldLength])<=[SN−RX_Next]modulo 2^([sn-FieldLength])<[RX_Next+AM_Window_Size−RX_Next] modulo2^([sn-FieldLength])) where sn-FieldLength is 12 or 18 for 12 bit SN and18 bit SN, respectively.

The transmitting side of the RLC entity 320, such as an AM RLC entity,may maintain the state variable 306, which may include a first statevariable, a second state variable, a third state variable, or acombination thereof. For example, the first state variable, the secondstate variable, and the third state variable may include anacknowledgement state variable (TX_Next_Ack), a send stat variable(TX_Next), and a poll send state variable (POLL_SN), respectively. Thefirst state variable, such as the acknowledgement state variable(TX_Next_Ack), may have a value of the SN of the next RLC SDU for whicha positive acknowledgment is to be received in-sequence, and may servesas the lower edge of the transmitting window. The first state variablemay initially set to 0, and may updated whenever the RLC entity receivesa positive acknowledgment for an RLC SDU with SN=TX_Next_Ack. The secondstate variable, such as the send state variable (TX_Next), may have avalue of the SN to be assigned for the next newly generated acknowledgemode data (AMD) PDU. The second state variable may initially be set to0, and may be updated whenever the RLC entity constructs an AMD PDU withSN=TX_Next and includes an RLC SDU or the last segment of a RLC SDU. Thethird state variable, such as the poll send state variable (POLL_SN),may have a value of the highest SN of the AMD PDU among the AMD PDUssubmitted to lower layer when POLL_SN is set. The third state variablemay initially be set to 0.

Additionally, the transmitting side of an RLC entity, such as an AM RLCentity, may maintain one or more counters. The one or more counters mayinclude a first counter, a second counter, a third counter, or acombination thereof. The first counter, the second counter, and thethird counter may include a PDU_WITHOUT_POLL counter, aBYTE_WITHOUT_POLL counter, a RETX_COUNT counter, respectively. The firstcounter, such as the PDU_WITHOUT_POLL counter may initially be set to 0and may be configured to count a number of AMD PDUs sent since a mostrecent poll bit was transmitted. The second counter, such as theBYTE_WITHOUT_POLL counter, may initially be set to 0, and may beconfigured to count a number of data bytes sent since the most recentpoll bit was transmitted. The third counter, such as the RETX_COUNTcounter, may be configured to count a number of retransmissions of anRLC service data unit (SDU) or RLC SDU segment. In some implementations,one RETX_COUNT counter may be maintained per RLC SDU.

The receive side of the RLC entity 320 may maintain the state variable306, which may include a fourth state variable, a fifth state variable,a sixth state variable, a seventh state variable, or a combinationthereof. For example, the fourth state variable, the fifth statevariable, the sixth state variable, and the seventh state variable mayinclude a receive state variable (RX_Next), a t-Reassembly statevariable (RX_Next_Status_Trigger), a maximum STATUS transmit statevariable (RX_Highest_Status), and a highest received state variable(RX_Next_Highest), respectively. The fourth state variable, such as thereceive state variable (RX_Next), may have a value of the SN followingthe last in-sequence completely received RLC SDU, and may serve as alower edge of a receiving window. The fourth state variable mayinitially set to 0, and may be updated whenever the RLC entity 320receives an RLC SDU with SN=RX_Next. The fifth state variable, such asthe t-Reassembly state variable (RX_Next_Status_Trigger), may have avalue of the SN following the SN of the RLC SDU which triggeredt-Reassembly. The sixth state variable, such as the maximum STATUStransmit state variable (RX_Highest_Status), may have a highest possiblevalue of the SN which can be indicated by “ACK_SN” when a STATUS PDUneeds to be constructed. The sixth state variable may initially be setto 0. The seventh state variable, such as the highest received statevariable (RX_Next_Highest) may have a value of the SN following the SNof the RLC SDU with the highest SN among received RLC SDUs. The seventhstate variable may initially be set to 0.

The transmitter 316 is configured to transmit reference signals, controlinformation and data to one or more other devices, and the receiver 318is configured to receive references signals, synchronization signals,control information and data from one or more other devices. Forexample, the transmitter 316 may transmit signaling, control informationand data to, and the receiver 318 may receive signaling, controlinformation and data from, the base station 105. In someimplementations, the transmitter 316 and the receiver 318 may beintegrated in one or more transceivers. Additionally or alternatively,the transmitter 316 or the receiver 318 may include or correspond to oneor more components of the UE 115 described with reference to FIG. 2 .For example, the transmitter 316 may include or correspond to theantennas 234 a-t, the modulator and demodulators 232 a-t, the transmitprocessor 220, the TX MIMO processor 230, or a combination thereof. Asanother example, the receiver 318 may include or correspond to theantennas 234 a-t, the modulator and demodulators 232 a-t, the MIMOdetector 236, the receive processor 238, or a combination thereof.

The RLC entity 320 is configured to set and update the state variable306. The UE 115 may establish the RLC entity 320 based on an upper layerrequest. For example, the UE 115 may establish the RLC entity 320 andmay set the state variable 306 to the initial value 308. Additionally,the UE 115 may re-establish the RLC entity 320 based on an upper layerre-establishment request. For example, to re-establish the RLC entity320, the UE may discard all RLC SDUs, RLC SDU segments, and RLC PDUs, ifany. Additionally, or alternatively, to re-establish the RLC entity 320,the UE 115 may stop and reset one or more timers, reset one or morestate variables to their initial values, or a combination thereof. Toillustrate, the UE 115 may stop and reset all timers and reset all statevariables to their initial values. Additionally, the RLC entity 320 maybe configured to have a mode, such as a transparent mode (TM), anunacknowledged mode (UM), or an AM. In some implementations, the statevariables 306 may be associated with a communication window used by theRLC entity 320 in the UM, such as an RLC UM entity. In some otherimplementations, the state variables 306 may be associated with acommunication window used by the RLC entity 320 in the AM, such as anRLC AM entity.

The base station 105 can include a variety of components (such asstructural, hardware components) used for carrying out one or morefunctions described herein. For example, these components can includeone or more processors 352 (hereinafter referred to collectively as “theprocessor 352”), one or more memory devices 354 (hereinafter referred tocollectively as “the memory 354”), one or more transmitters 356(hereinafter referred to collectively as “the transmitter 356”), and oneor more receivers 358 (hereinafter referred to collectively as “thereceiver 358”). The processor 352 may be configured to executeinstructions stored in the memory 354 to perform the operationsdescribed herein. In some implementations, the processor 352 includes orcorresponds to one or more of the receive processor 238, the transmitprocessor 220, and the controller 240, and the memory 354 includes orcorresponds to the memory 242.

The memory 354 includes or is configured to store one or more statevariables 355 (hereinafter referred to collectively as “the statevariable 355”) and the initial value 308. The state variable 355 mayinclude or correspond to the state variable 306. For example, the basestation 105 may maintain a current value of the state variable 355during a communication session. In some implementations, the basestation 105 may initiate a communication session and set the statevariable 355 to the initial value 308. Additionally, or alternative,during the communication session, the base station 105 may adjust thevalue of the state variable 355 such that the base station 105 maintainsa current value of the state variable 355.

The transmitter 356 is configured to transmit reference signals,synchronization signals, control information and data to one or moreother devices, and the receiver 358 is configured to receive referencesignals, control information and data from one or more other devices.For example, the transmitter 356 may transmit signaling, controlinformation and data to, and the receiver 358 may receive signaling,control information and data from, the UE 115. In some implementations,the transmitter 356 and the receiver 358 may be integrated in one ormore transceivers. Additionally or alternatively, the transmitter 356 orthe receiver 358 may include or correspond to one or more components ofbase station 105 described with reference to FIG. 2 . For example, thetransmitter 356 may include or correspond to the antennas 252 a-r, themodulator and demodulators 254 a-r, the transmit processor 264, the TXMIMO processor 266, or a combination thereof. As another example, thereceiver 358 may include or correspond to the antennas 252 a-r, themodulator and demodulators 254 a-r, the MIMO detector 256, the receiveprocessor 258, or a combination thereof.

The base station 360 may include one or more components as describedwith reference to the base station 105. Additionally, or alternatively,the base station 360 may be configured to perform one or more operationsas described with reference to the base station 105.

The content provider 362 is configured to provide content, such as videocontent, audio content, or a combination thereof. The content may beassociated with a communication session, such as a communication sessionestablished with the UE 115. For example, the UE 115 may establish acommunication session, such as a unicast communication session, amulticast communication session, or a broadcast communication session,with the content provider 352 via one or more base stations, such as thebase station 105 or the base station 360. Although the wirelesscommunications system 300 is described as the content provider 362 beseparate from the base station 105, in other implementations, the basestation 105 may include the content provider 362 or the content of thecontent provider 262. Additionally, although the wireless communicationssystem 300 is described as including the content provider 362, in otherimplementations, the wireless communication system 300 may not includethe content provider 362.

In some implementations, the wireless communications system 300implements a 5G New Radio (NR) network. For example, the wirelesscommunications system 300 may include multiple 5G-capable UEs 115 andmultiple 5G-capable base stations 105, such as UEs and base stationsconfigured to operate in accordance with a 5G NR network protocol suchas that defined by the 3GPP.

During operation of the wireless communications system 300, the UE 115may establish the RLC entity 320 and configure a mode of the RLC entity320. For example, to configure the RLC entity, the UE 115 may establishthe RLC entity 320 to join an ongoing communication session, such as aunicast communication session, a multicast communication session, or abroadcast communication. In some implementations, the communicationsession includes a multicast data session. Additionally, oralternatively, to establish the RLC entity, the UE 115 may set the statevariable 306 to the initial value 308. The state variable 306 may beassociated with a communication window, such as a Tx window, an Rxwindow, or a combination thereof, of a communication session. Forexample, the state variable may include a window size of thecommunication window, a lower edge value for the communication window,an upper edge value for the communication window, at least one of thefirst through seventh state variables, or a combination thereof. Theinitial value 308 may be based on a standard, equal to zero, or acombination thereof. Additionally, or alternatively, the initial values308 may be included in or indicated by a radio resource control (RRC)message that is transmitted by the base station 105 and received by theUE 115. In some implementations, the UE 115 may initiate establishmentof the communication session after configuring the RLC entity 320.

In some implementations, the base station 105 may also establish a RLCentity that is associated with the communication session. In someimplementations, a transmit RLC entity of the base station 105 may besynchronized with the RLC entity 320, such as a receive RLC entity, ofthe UE 115. Additionally, or alternatively, a receive RLC entity of thebase station 105 may be synchronized with the RLC entity 320, such as atransmit RLC entity, of the UE 115. Synchronization of an RLC entity ofthe base station 105 and the RLC entity 320 of the UE may includesynchronization of an RLC sliding window movement in time such the anRLC sliding window of the base station 105 and an RLC sliding window ofthe UE 115 entirely or at least partially overlap in time.

After configuration of the RLC entity 320, the base station 105 maygenerate a control message 370, such as an RLC control message. Thecontrol message 370 may include an indication of a first value 371 ofthe state variable 355 maintained by the base station 105 and associatedwith a communication window of the communication session. The firstvalue 371 may enable synchronization of the communication window of thecommunication window of the UE 115 and may be different than the initialvalue 308, a value of the state variable 306, or both. After generationof the control message 370, the base station 105 transmits the controlmessage 370 to the UE 115. In some implementations, the control message370, such as the first value 371, may include or indicate the initialvalue 308.

In some implementations, the control message 370 includes a first RLCPDU sent to the UE 115 after establishment of the RLC entity 320. Forexample, the control message 370 may include a synchronization PDU thatincludes the indication. In some implementations, the control message370 may be included in an RRC message. Additionally, or alternatively,the control message 370 may include a control PDU type (CPT) filed thatincludes one or more bits. The one or more bits may indicate the type asan RLC control PDU, or a synchronization PDU, that includes the firstvalue 371. Additionally, or alternatively, the control message 370transmitted by the base station 105 may be independent of an RLC SN.Stated in another manner, the control message 370 may not include an RLCSN.

The UE 115 receives the control message 370 including the indication ofthe first value 371. The UE 115 may set the state variable 306 based oncontrol message 370. For example, the UE 115 may set the state variable306 from the initial value 308, or a current value, to the first value371. Setting the state variable 306 to the first value 371 maysynchronize the communication window (associated with the RLC entity320) of the UE 115 with the base station 105. After setting the statevariable 306, the UE 115 may receive or transmit a packet associatedwith the communication session within the communication window based onthe state variable 306. To illustrate, the UE 115 may receive a packet372 associated with the communication session from the base station 105.

In some implementations, the UE 115 may perform a handover operationfrom the base station 360 to the base station 115. For example, the UE115 may send a handover request 378 to the base station 360 to initiatethe handover operation from a first cell associated with the basestation 360 to a second cell, such as a target cell, associated with thebase station 105. To illustrate, the UE 115 may have established the RLCentity and joined the communication session the base station 360 and mayperform the handover operation to continue the communication session viathe base station 105.

After the handover operation, the UE 115 may re-establishing the RLCentity 320, such as an RLC UM entity or an RLC AM entity, based oncompletion of the handover operation to the target cell, such as thebase station 105. The UE 115 may receive control message 370, such as anRLC control message, after the RLC entity 320 is re-established. Forexample, in some implementations, the UE 115 may receive initial statevariables, such as initial value 308, in an RRC message. In someimplementations, the control message 370 transmitted by the base station105 after completion of the handover operation may include an RLC dataPDU that includes an assigned RLC SN. Alternatively, the control message370 transmitted by the base station 105 after completion of the handoveroperation may be independent of an RLC SN. Stated in another manner, thecontrol message 370 may not include an RLC SN. In some implementations,after the RLC entity 320 is re-established, the UE 115 may receive amessage that includes a SN and may determine or generate state variablesbased on the received SN.

Based on the control message 370 received after completion of thehandover operation, the UE 115 may set the state variable 306 based onthe received control message 370. After setting the state variable 306,the UE 115 may receive or transmit a packet associated with thecommunication session within the communication window based on the statevariable 306. To illustrate, the UE 115 may receive a packet 372associated with the communication session from the base station 105.

In some implementations, the base station 105 may determine whether theUE 115 joined the communication session or completed a handoveroperation. The base station 105 may generate and transmit the controlmessage 370 the UE 115 based on a determine that the UE joined thecommunication session or completed a handover operation.

In some implementations, the base station 105 may generate one or moresynchronization (sync) messages, such as one or more synchronizationPDUs, during the communication session. For example, the one or moresynchronization messages may include a representative synchronizationmessage 374. Each of the one or each of the one or more synchronizationmessage may include a respective indication of a corresponding update ofthe state variable 306 of the UE 115, a respective sequence number, or acombination thereof. To illustrate, the synchronization message 374 mayinclude a second value 375 of the state variable 355 maintained by thebase station 105 and associated with a communication window of thecommunication session. The second value 375 may enable synchronizationof the communication window of the communication window of the UE 115and may be different than a value of the state variable 306. Forexample, the UE 115 may experience fading conditions and thesynchronization message 374 including the second value 375 may enablethe UE 115 to quickly adjust state variable 306 and come back insynchronization with the ongoing communication session, such as amulticast service. In some implementations, the synchronization message374 may include a SN number 377.

After generation of a synchronization message, such as thesynchronization message 374, the base station 105 may transmit thesynchronization message to the UE 115. The UE 115 may receive thesynchronization message and determine whether or not to update the statevariable 306 based on indication of the corresponding update of thestate variable 306. For example, the UE 115 may determine to update thestate variable 306 and may update the state variable based on thereceived synchronization message, such as based on the received secondvalue 375. In some implementations, the base station 105 periodicallytransmits a synchronization message to the UE 115 to enable the UE 115to maintain synchronization of the communication window (of the UE 115)with the base station 105. In some implementations, the sync message 374may be a control PDU included in or coupled to, such as piggyback to, adata PDU.

Although synchronization of the command window has been described andbeing maintained based on the control message 370 and thesynchronization message 374, either of the control message 370 orsynchronization message 374 may be utilized without the other.Additionally, although the control message 370 has been described asbeing provided based on the UE 115 joining the communications sessionand completing a handover operation, in other implementations, thecontrol message 370 may be provided for one of joining thecommunications session and completing the handover operation, but notthe other.

As described with reference to FIG. 3 , the present disclosure providestechniques for management of state variable 306. In some aspects, thepresent disclosure provides management of the state variable 306 byproviding the control message 370 that includes the first value 371. Forexample, the control message 370 may be provided based on establishmentor re-establishment of the RLC entity 320 at the UE 115. Additionally,or alternatively, the present disclosure provides management of thestate variable 306 by providing the synchronization message 374 thatincludes the second value 375. Each of the control message 370 and thesynchronization message 374 enable the UE 115 to maintainsynchronization with the base station 115. By maintainingsynchronization between the UE 115 and the base station 105, the UE 115may experience fewer interruptions during the communication session andthereby provide a positive user experience.

FIG. 4 is a block diagram of an example wireless communications system400 that supports management of a state variable according to one ormore aspects. In some examples, the wireless communications system 400may implement aspects of the wireless network 100 or the wirelesscommunications system 300. The wireless communications system 400includes the UE 115, the base station 105, a base station 360, and acontent provider 352. Although one UE 115 and two base station 105 and360 are illustrated, in some other implementations, the wirelesscommunications system 400 may generally include multiple UEs 115, andmay include one base station or more than two base stations. In someimplementations, the base station 105 may be associated with a firstcell and the base station 360 may be associated with a second cell. Insome other implementations, the base station 105 is associated with afirst cell and a second cell.

The UE 115 can include a variety of components (such as structural,hardware components) used for carrying out one or more functionsdescribed herein. For example, these components can include theprocessor 302, the memory 304, the transmitter 316, the receiver 318,and a PDCP entity 422. The processor 302 may be configured to executeinstructions stored in the memory 304 to perform the operationsdescribed herein. In some implementations, the processor 302 includes orcorresponds to one or more of the receive processor 258, the transmitprocessor 264, and the controller 280, and the memory 304 includes orcorresponds to the memory 282.

The memory 304 includes or is configured to store one or more statevariables 406 (hereinafter referred to collectively as “the statevariable 406”), one or more initial values 408 (hereinafter referred tocollectively as “the initial value 408”). In some implementations, thestate variable 406 and the initial value 408 may include or correspondto the state variable 306 and the initial value 308, respectively. Thestate variable 406 may be associated with operation of or communicationvia the PDCP entity 422, such as a communication window. For example,the state variable 406 may include a window size, a lower edge value, anupper edge value, or a combination thereof.

The state variable 406 may include or correspond to a data transfer,such as an PDU transfer associated with a PDCP layer. For example, theUE 115 may maintain a current value of the state variable 406 during acommunication session. In some implementations, the UE 115 may initiatea communication session and set the state variable 406 to the initialvalue 408. For example, the UE 115 may set the state variable 406 to theinitial value 408 based on establishment or re-establishment of the PDCPentity 422. Additionally, or alternative, during the communicationsession, the UE 115 may adjust the value of the state variable 406 asdescribe further herein.

The state variable 406 may be set to a non-negative integer. As anillustrative, non-limiting example, state variable 406 is describedherein with reference to a PDCP PDU data transfer. State variables 406may have a value from 0 to an upper limit, such as [232−1].Additionally, or alternatively, PDCP data PDUs may be numbered integersequence numbers (SNs), which cycle through a field: 0 to[2[pdcp-SN-size]−1]. In some implementations, pdcp-SN-size may be basedon or equal to the upper limit.

The transmitting side of the PDCP entity 422 may maintain the statevariable 406, which may include a first state variable. For example, thefirst state variable may include a transmit (Tx) next state variable(TX_Next). The first state variable, such as the Tx next state variable(TX_Nex), may have a value that indicates a count value of a next PDCPSDU to be transmitted. The first state variable may initially be set to0.

The receive side of the PDCP entity 422 may maintain the state variable306, which may include a second state variable, a third stat variable, afourth state variable, or a combination thereof. For example, the secondstate variable, the third state variable, and the fourth state variablemay include a receive (Rx) state variable (RX_Next), an Rx deliver statevariable (RX_DELIV), and an Rx reorder state variable (RX_REORD),respectively. The second state variable, such as the Rx state variable(RX_Next), may have a value that indicates a count of a next PDCP SDUexpected to be received. The second state variable may initially set to0. The third state variable, such as the Rx deliver state variable(RX_DELIV), may have a value that indicates a count value of the firstPDCP SDU not delivered to the upper layers, but still waited for. Thethird state variable may be initially set to 0. The fourth statevariable, such as the Rx reorder state variable (RX_REORD), may have avalue that indicates a count associated with a PDCP data PDU whichtriggered reordering, such as t-reordering.

The PDCP entity 422 is configured to set and update the state variable406. The UE 115 may establish the PDCP entity 422 as part of a stack.For example, the UE 115 may establish the stack or the PDCP entity 422based on an upper layer request. The stack may include or correspond toa service data adaptation protocol (SDAP) layer, packet data convergenceprotocol (PDCP) layer, an RLC layer, a media access control (MAC) layer,or a physical (PHY) layer. To illustrate, the UE 115 may establish thePDCP entity 422 and may set the state variable 306 to the initial value308. Additionally, or alternatively, the UE 115 may also establish theRLC entity 320 based on the upper layer request. In some implementation,the UE 115 may additionally re-establish the PDCP entity 422 (or the RLCentity 320) based on an upper layer re-establishment request.

The base station 105 can include a variety of components (such asstructural, hardware components) used for carrying out one or morefunctions described herein. For example, these components can includethe processor 352, the memory 354, the transmitter 356, and the receiver358. The processor 352 may be configured to execute instructions storedin the memory 354 to perform the operations described herein. In someimplementations, the processor 352 includes or corresponds to one ormore of the receive processor 238, the transmit processor 220, and thecontroller 240, and the memory 354 includes or corresponds to the memory242.

The memory 354 includes or is configured to store one or more statevariables 455 (hereinafter referred to collectively as “the statevariable 455”) and the initial value 408. The state variable 455 mayinclude or correspond to the state variable 355. Additionally, oralternatively, the state variable 455 may include or correspond to thestate variable 406. For example, the base station 105 may maintain acurrent value of the state variable 455 during a communication session.In some implementations, the base station 105 may initiate acommunication session and set the state variable 455 to the initialvalue 408. Additionally, or alternative, during the communicationsession, the base station 105 may adjust the value of the state variable455 such that the base station 105 maintains a current value of thestate variable 455.

In some implementations, the base station 105 may include a PDCP entity.The PDCP entity may include or correspond to the PDCP entity 422. Thetransmitting PDCP entity of the base station 105 may be configured toperform operations associated with transmission of data to the receivingPDCP entity, such as the PDCP entity 422, of the UE 115. Additionally,or alternatively, the receiving PDCP entity of the base station 105 maybe configured to perform operations associated with reception of datafrom the transmitting PDCP entity, such as the PDCP entity 422, of theUE 115.

In some implementations, the wireless communications system 400implements a 5G NR network. For example, the wireless communicationssystem 400 may include multiple 5G-capable UEs 115 and multiple5G-capable base stations 105, such as UEs and base stations configuredto operate in accordance with a 5G NR network protocol such as thatdefined by the 3GPP.

During operation of the wireless communications system 400, the UE 115may establish the PDCP entity 422. For example, to configure the PDCPentity 422, the UE 115 may establish the PDCP entity 422 to join anongoing communication session, such as a unicast communication session,a multicast communication session, or a broadcast communication. In someimplementations, the communication session includes a multicast datasession. In such implementations, the U 115 may configure a multicastbearer (MRB) that includes or corresponds to a user plane stack havingone or more layers, such as a SDAP layer, a PDCP layer, an RLC layer, aMAC layer, a PHY layer, or a combination thereof. Additionally, oralternatively, to establish the PDCP entity 422, the UE 115 may set thestate variable 406 to the initial value 408. The state variable 406 maybe associated with a communication window, such as a Tx window, an Rxwindow, or a combination thereof, of a communication session. Forexample, the state variable may include a window size of thecommunication window, a lower edge value for the communication window,an upper edge value for the communication window, at least one of thefirst through fourth state variables, or a combination thereof. Theinitial value 408 may be based on a standard, equal to zero, or acombination thereof. Additionally, or alternatively, the initial values408 may be included in or indicated by an RRC message that istransmitted by the base station 105 and received by the UE 115. In someimplementations, the UE 115 may initiate establishment of thecommunication session after configuring the PDCP entity 422.

In some implementations, the base station 105 may also establish a PDCPentity that is associated with the communication session. In someimplementations, a transmit PDCP entity of the base station 105 may besynchronized with the PDCP entity 422, such as a receive RLC entity, ofthe UE 115. Additionally, or alternatively, a receive PDCP entity of thebase station 105 may be synchronized with the PDCP entity 422, such as atransmit PDCP entity, of the UE 115. Synchronization of a PDCP entity ofthe base station 105 and the PDCP entity 422 of the UE 115 may includesynchronization of an PDCP sliding window movement in time such the aPDCP sliding window of the base station 105 and a PDCP sliding window ofthe UE 115 entirely or at least partially overlap in time.

After configuration of the PDCP entity 422, the base station 105 maygenerate a control message 470, such as a PDCP control message. In someimplementations, generation or transmission of the control message 470may be part of establishment of the communication session. Additionally,or alternatively, the control message 470 may be included in an RRCmessage. To illustrate, the base station 105 may generate the RRCmessage that includes the control message 370, the control message 470,or a combination thereof. The control message 470 may include anindication of a first value 471 of the state variable 455 maintained bythe base station 105 and associated with a communication window of thecommunication session. The first value 471 may enable synchronization ofthe communication window of the communication window of the UE 115 andmay be different than the initial value 408, a value of the statevariable 406, or both. After generation of the control message 470, thebase station 105 transmits the control message 470 to the UE 115. Insome implementations, the control message 470, such as the first value471, may include or indicate the initial value 408.

In some implementations, the control message 470 includes a first PDCPPDU sent to the UE 115 after establishment of the PDCP entity 422. Forexample, the control message 470 may include a synchronization PDU thatincludes the first value 471. Additionally, or alternatively, thecontrol message 470 may include an RRC that includes the first value471. In some implementations, the first value 471 includes the secondstate variable (Rx_Next), the third state variable (Rx_DELIV), a valueassociated with a lower edge of a communication window, a valueassociated with an upper edge of the communication window, or acombination thereof.

In some implementations, the UE 115 may establish the communicationsession such that the UE 115 joins an ongoing multicast session in whichthe base station 105 includes a PDCP entity having a current value ofthe state variable 455. When the UE 115 joins the ongoing multicastsession UE establishes with the state variable 406 set to the initialvalue 408, a mis-match may occur between the 115 UE variable 406 and thebase station state variable 455, such that a communication window of theUE 115 and a communication window of the base station 105 are out ofsynchronization. When a mis-match is presents such that thecommunication windows are out of synchronization, the UE 115 may missdata transmitted by the base station 105.

The UE 115 receives the control message 470 including the indication ofthe first value 471. The UE 115 may set the state variable 406 based oncontrol message 470. For example, the UE 115 may set the state variable406 from the initial value 408, or a current value, to the first value471. Setting the state variable 406 to the first value 471 maysynchronize the communication window (associated with the PDCP entity422) of the UE 115 with the base station 105. After setting the statevariable 406, the UE 115 may receive or transmit data, such as PDCPdata, associated with the communication session within the communicationwindow based on the state variable 406. To illustrate, the UE 115 mayreceive a PDCP data PDU associated with the communication session fromthe base station 105.

In some implementations, the UE 115 may perform a handover operationfrom the base station 360 to the base station 115. For example, the UE115 may send a handover request 478 to the base station 360 to initiatethe handover operation from a first cell associated with the basestation 360 to a second cell, such as a target cell, associated with thebase station 105. To illustrate, the UE 115 may have established thePDCP entity 422 and joined the communication session the base station360 and may perform the handover operation to continue the communicationsession via the base station 105.

After the handover operation, the UE 115 may re-establishing the PDCPentity 422 based on completion of the handover operation to the targetcell, such as the base station 105. The UE 115 may receive the controlmessage 470, such as a PDCP control message, after the PDCP entity 422is re-established. For example, the UE 115 may receive initial statevariables, such as initial state variables 408, in an RRC message. Insome implementations, the control message 470 transmitted by the basestation 105 after completion of the handover operation may include aPDCP data PDU. In some implementations, after the PDCP entity 422 isre-established, the UE 115 may receive a message that includes a SN andmay determine or generate state variables based on the received SN.

Based on the control message 470 received after completion of thehandover operation, the UE 115 may set the state variable 406 based onthe received control message 470. After setting the state variable 406,the UE 115 may receive or transmit a data, such as PDCP data, associatedwith the communication session within the communication window based onthe state variable 406.

In some implementations, the base station 105 may determine whether theUE 115 joined the communication session or completed a handoveroperation. The base station 105 may generate and transmit the controlmessage 470 the UE 115 based on a determine that the UE joined thecommunication session or completed a handover operation.

In some implementations, the base station 105 may generate one or moresynchronization (sync) messages, such as one or more synchronizationPDUs, during the communication session. For example, the one or moresynchronization messages may include a representative synchronizationmessage 474. Each of the one or each of the one or more synchronizationmessage may include a respective indication of a corresponding update ofthe state variable 406 of the UE 115. To illustrate, the synchronizationmessage 374 may include a second value 475 of the state variable 45maintained by the base station 105 and associated with a communicationwindow of the communication session. In some implementations, the secondvalue 475 includes the second state variable (Rx_Next), the third statevariable (Rx_DELIV), a value associated with a lower edge of acommunication window, a value associated with an upper edge of thecommunication window, or a combination thereof. The second value 475 mayenable synchronization of the communication window of the communicationwindow of the UE 115 and may be different than a value of the statevariable 406. For example, the UE 115 may experience fading conditionsand the synchronization message 474 including the second value 475 mayenable the UE 115 to quickly adjust state variable 406 and come back insynchronization with the ongoing communication session, such as amulticast service.

After generation of a synchronization message, such as thesynchronization message 474, the base station 105 may transmit thesynchronization message to the UE 115. The UE 115 may receive thesynchronization message and determine whether or not to update the statevariable 406 based on indication of the corresponding update of thestate variable 406. For example, the UE 115 may determine to update thestate variable 406 and may update the state variable based on thereceived synchronization message, such as based on the received secondvalue 475. In some implementations, the sync message 474 may be acontrol PDU included in or coupled to, such as piggyback to, a data PDU.

In some implementations, the base station 105 periodically transmits asynchronization message to the UE 115 to enable the UE 115 to maintainsynchronization of the communication window (of the UE 115) with thebase station 105. Additionally, or alternatively, the base station 105may generate or transmit the sync message 474 based on determination ofan event. The event may include or correspond to an indication that theUE 115 is gone through some fading and returned to good radioconditions, such as having a physical layer that has gone fromout-of-sync to in-sync, resulting in one or more lost packets andcommunication windows of the UE 115 and the base station 105 beingunsynchronized. As another example, the event may include or correspondto the base station 105 determining that retransmissions are exhaustedfor an edge of the packets, such that the lower edge of the UE 115 needsto be moved to avoid additional retransmissions. As another example,determination of the event may be based on a load balancing orretransmission policy. As a further example, if the UE 115 is configuredfor RLC UM, the event may be determined based on packet loss at the PDCPlevel, which may occur even in good radio conditions if the PDCP windowof the UE 115 is mis-aligned with the PDCP window of the base station105. Another example of the event may be PDCP activation from asuspension of PDCP operations.

Although synchronization of the command window has been described andbeing maintained based on the control message 470 and thesynchronization message 474, either of the control message 470 orsynchronization message 474 may be utilized without the other.Additionally, although the control message 470 has been described asbeing provided based on the UE 115 joining the communications sessionand completing a handover operation, in other implementations, thecontrol message 470 may be provided for one of joining thecommunications session and completing the handover operation, but notthe other.

In some implementations, the control message 470 or the sync message 474may include a control PDU type (CPT) filed that includes one or morebits. The one or more bits may indicate the type of control informationincluded in the control message 470, such as a PDCP control PDU. In someimplementations, the one or more bits may have a first value, such as000, which indicates the type of control information included in thecontrol message 470 or the sync message 474 is a PDCP status report. Asanother example, the one or more bits may have a second value, such as a001, which indicates the type of control information included in thecontrol message 470 or the sync message 474 is interspersed robustheader compression (ROHC) feedback. As another example, the one or morebits may have a third value, such as 010, which indicates the type ofcontrol information included in the control message 470 or the syncmessage 474 is a synchronization PDU, such as a PDCP MRB synchronizationPDU.

As described with reference to FIG. 4 , the present disclosure providestechniques for management of state variable 406. In some aspects, thepresent disclosure provides management of the state variable 406 byproviding the control message 470 that includes the first value 471. Forexample, the control message 470 may be provided based on establishmentor re-establishment of the PDCP entity 422 at the UE 115. Additionally,or alternatively, the present disclosure provides management of thestate variable 406 by providing the synchronization message 474 thatincludes the second value 475. Each of the control message 470 and thesynchronization message 474 enable the UE 115 to maintainsynchronization with the base station 115. By maintainingsynchronization between the UE 115 and the base station 105, the UE 115may experience fewer interruptions during the communication session andthereby provide a positive user experience.

FIG. 5 is a flow diagram illustrating an example process 500 thatsupports management of a state variable according to one or moreaspects. Operations of the process 500 may be performed by a UE, such asthe UE 115 described above with reference to FIGS. 1-4 or a UE asdescribed with reference to FIG. 6 . For example, example operations(also referred to as “blocks”) of the process 500 may enable the UE 115to manage a state variable.

In block 502, the UE initializes a set of state variables to a first setof initial values, respectively. The set of state variables areassociated with synchronization of a communication window of acommunication session. For example, the set of state variables mayinclude or correspond to the state variable 306 or 406. The first set ofinitial values may include or correspond to the initial value 308 or408. The communication session may include a unicast communicationsession, a multicast communication session, or a broadcastcommunication. For example, the communication session may be themulticast communication session.

In some implementations, the communication window may include a Txwindow, an Rx window, or a combination thereof. Additionally, oralternatively, the set of state variables include a window size of thecommunication window, a lower edge value for the communication window,an upper edge value for the communication window, or a combinationthereof. In some implementations, the set of state variables include awindow size of the communication window, and a lower edge value for thecommunication window or an upper edge value for the communicationwindow.

In block 504, the UE receives a control message including an indicationof a second set of current values associated with respective statevariables of the set of state variables. At least one of the currentvalues being different than a respective one of the initial values. Forexample, the control message and the indication may include orcorrespond to the control message 370 and the first value 371,respectively, or the control message 470 and the first value 471,respectively. In some implementations, the indication of the second setof current values may be generated by a base station, such as the basestation 105, based on one or more state variables maintained by the basestation.

In block 506, the UE sets the set of state variables to the second setof current values to synchronize the communication window with thecommunication session. In some implementations, setting the set of statevariables based on the indication includes adjusting the set of statevariables from the first set of initial values to the second set ofcurrent values, or to a third set of value base on the second set ofcurrent values.

In some implementations, the UE, after setting the set of statevariables, receives or transmits a packet associated with thecommunication session within the communication window based on thesynchronized communication window. For example, the packet may includeor correspond to the packet 372.

In some implementations, the set of state variables corresponds to anRLC AM entity. The UE may configure the RLC AM entity, which may includesetting the set of state variables to the set of respective initialvalues. The set of respective initial values may be based on a standard.In some implementations, at least one value of the set of respectiveinitial values is zero. Additionally, or alternatively, the UE may joinan ongoing multicast data session corresponding to the communicationsession.

In some implementations, the control message includes an RLC controlmessage. The RLC control message may be included in an RLC PDU receivednext in time after completion of configuring the RLC AM entity.Additionally, the UE may initiate establishment of the communicationsession after configuring the RLC AM entity.

In some implementations, after configuring the RLC AM entity, the UE mayperform a handover operation to a target cell. For example, the UE mayperform a handover operation from a first cell to a second cell, such asthe target cell. The UE may re-establish the RLC AM entity based oncompletion of the handover operation to the target cell. In some suchimplementations, the RLC control message is received after the RLC AMentity is re-established.

In some implementations, the control message includes a synchronizationPDU that includes the indication. The UE may update the set of statevariables, in response to receiving one synchronization PDU of the oneor more synchronization PDUs, based on the respective indicationincluded in the received one synchronization PDU. In someimplementations, the control message may be included in a data PDU thatincludes an assigned RLC SN. The RLC SN may include or correspond to thesequence number 377.

In some implementations, after setting the set of state variables basedon the indication and during the communication session, the UE mayreceive one or more synchronization PDUs. The one or moresynchronization PDUs may include or correspond to the synchronizationmessage 374 or 474. In some implementations, each of the one or morereceived synchronization PDUs include a respective indication of acorresponding update of the one or more state variables. For example,the indication may include or correspond to the second value 375 or 475.The UE may update the set of state variables based on the indicationincluded in a particular synchronization PDU of the one of the one ormore synchronization PDUs. In some implementations, the one or moresynchronization PDUs include multiple synchronization PDUs transmittedperiodically.

FIG. 6 is a block diagram of an example UE 600 that supports managementof a state variable according to one or more aspects. The UE 600 may beconfigured to perform operations, including the blocks of the process500 described with reference to FIG. 5 . In some implementations, the UE600 includes the structure, hardware, and components shown and describedwith reference to the UE 115 of FIG. 2, 3 , or 4. For example, the UE600 includes the controller 280, which operates to execute logic orcomputer instructions stored in the memory 282, as well as controllingthe components of the UE 600 that provide the features and functionalityof the UE 600. The UE 600, under control of the controller 280,transmits and receives signals via wireless radios 601 a-r and theantennas 252 a-r. The wireless radios 601 a-r include various componentsand hardware, as illustrated in FIG. 2 for the UE 115, including themodulator and demodulators 254 a-r, the MIMO detector 256, the receiveprocessor 258, the transmit processor 264, and the TX MIMO processor266.

As shown, the memory 282 may include state variable logic 602 and entitylogic 603. The state variable logic 602 may be configured to set,adjust, update, or synchronize one or more state variables, such asstate variable 306 or 406. The entity logic 603 may be configured toreceive or process one or more received messages, such as the controlmessage 370 or 470, the packet 372, the synchronization message 374 or474, or a combination thereof. The UE 600 may receive signals from ortransmit signals to one or more network entities, such as the basestation 105 of FIGS. 1-4 , the base station 360 of FIG. 3 or, or a basestation as illustrated in FIG. 8 .

In some implementations, the UE 600 may be configured to perform theprocess 500 of FIG. 5 . To illustrate, the UE 600 may execute, undercontrol of the controller 280, the state variable logic 602 and theentity logic 603 stored in the memory 282. The execution environment ofthe state variable logic 602 provides the functionality to perform atleast the operations in block 502, in block 506, or a combinationthereof. The execution environment of the entity logic 603 provides thefunctionality to perform at least the operations in block 504.

FIG. 7 is a flow diagram illustrating an example process 700 thatsupports management of a state variable according to one or moreaspects. Operations of the process 700 may be performed by a basestation, such as the base station 105 described above with reference toFIGS. 1-4 , the base station 360 as described above with reference toFIG. 3 or 4 , or a base station as described with reference to FIG. 8 .For example, example operations of the process 700 may enable the basestation to manage a state variable.

In block 702, the base station generating a control message including anindication of a set of values of a set of state variables associatedwith a communication window of a communication session. The set ofvalues enable synchronization of the communication window and aredifferent from a set of initial values of the set of state variables.For example, the control message may include or correspond to thecontrol message 371. The set of value may include or correspond to thefirst value 371. The set of initial values may include or correspond tothe initial value 308 or 408.

In some implementations, the control messages is associated with an RLCentity of the UE. For example, the entity may include or correspond toRLC entity 320 or PDCP 422. In some implementations, the entity mayinclude an RLC AM entity.

In block 704, the base station transmitting the control message to a UE.For example, the UE may include or correspond to the UE 115. In someimplementations, after transmitting the control message, the basestation may transmit or receive a packet associated with thecommunication session. For example, the packet may include or correspondto the packet 372.

In some implementations, the communication session includes a unicastcommunication session, a multicast communication session, or a broadcastcommunication. For example, the communication session may be themulticast communication session. Additionally, or alternatively, thecommunication window includes a Tx window, an Rx window, or acombination thereof. Additionally, the one or more state variables mayinclude a window size of the communication window, a lower edge valuefor the communication window, an upper edge value for the communicationwindow, or a combination thereof.

In some implementations, the base station may determine whether the UEjoined the communication session or completed a handover operation.Additionally, or alternatively, the base station may transmit thecontrol message to the UE based on a determine that the UE joined thecommunication session or completed a handover operation. In someimplementations, the control message may be transmitted to the UEindependent of a sequence number associated with the communicationsession.

In some implementations, the base station may generate one or moresynchronization PDUs. At least one of the one or more synchronizationPDUs may include or correspond to the synchronization message 374 or474. In some implementations, each of the one or more synchronizationPDUs include a respective indication of a corresponding update of theone or more state variables. The indication of the corresponding of theset of state variables may include or correspond to the second value 375or 475. The base station may transmit the one or more synchronizationPDUs. In some implementations, the one or more synchronization PDUs mayinclude multiple synchronization PDUs transmitted periodically.Additionally, or alternatively, each synchronization PDU of the one ormore synchronization PDUs may be included in a respective RLC data PDUthat includes an RLC SN assigned based on the communication session. TheRLC SN may include or correspond to the sequence number 377.

FIG. 8 is a block diagram of an example base station 800 that supportsmanagement of a state variable according to one or more aspects. Thebase station 800 may be configured to perform operations, including theblocks of the process 700 described with reference to FIG. 7 . In someimplementations, the base station 800 includes the structure, hardware,and components shown and described with reference to the base station105 of FIGS. 1-4 or the base station 360 of FIG. 3 or 4 . For example,the base station 800 may include the controller 240, which operates toexecute logic or computer instructions stored in the memory 242, as wellas controlling the components of the base station 800 that provide thefeatures and functionality of the base station 800. The base station800, under control of the controller 240, transmits and receives signalsvia wireless radios 801 a-t and the antennas 234 a-t. The wirelessradios 801 a-t include various components and hardware, as illustratedin FIG. 2 for the base station 105, including the modulator anddemodulators 232 a-t, the transmit processor 220, the TX MIMO processor230, the MIMO detector 236, and the receive processor 238.

As shown, the memory 242 may include state variable logic 802, messagegeneration logic 803, and transmission logic 804. The state variablelogic 802 may be configured to set, adjust, and update one or more statevariables, such as state variable 355 or 455. The message generationlogic 803 may be configured to generate one or more messages, such asthe control message 370 or 470, the packet 372, the synchronizationmessage 374 or 474, or a combination thereof. The transmission logic 804may be configured to transmit one or more messages generated by themessage generation logic 803. The base station 800 may receive signalsfrom or transmit signals to one or more UEs, such as the UE 115 of FIGS.1-4 or the UE 700 of FIG. 7 .

In some implementations, the base station 800 may be configured toperform the process 700 of FIG. 7 . To illustrate, the base station 800may execute, under control of the controller 240, the state variablelogic 802, the message generation logic 803, or the transmission logic804 stored in the memory 242. The execution environment of the statevariable logic 802 provides the functionality to perform at least theoperations associated with block 702. The execution environment of themessage generation logic 803 provides the functionality to perform atleast the operations in block 702. The execution environment of thetransmission logic 804 provides the functionality to perform at leastthe operations in block 704.

It is noted that one or more blocks (or operations) described withreference to FIG. 5 or 7 may be combined with one or more blocks (oroperations) described with reference to another of the figures. Forexample, one or more blocks (or operations) of FIG. 5 may be combinedwith one or more blocks (or operations) of FIG. 7 . As another example,one or more blocks associated with FIG. 4 or 7 may be combined with oneor more blocks (or operations) associated with FIG. 1, 2, 3 , or 4.Additionally, or alternatively, one or more operations described abovewith reference to FIG. 1, 2, 3 , or 4 may be combined with one or moreoperations described with reference to FIG. 6 or 8 .

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In a firstaspect, techniques for enabling management of a state variable a mayinclude initializing one or more state variables associated with an RLCentity to a set of one or more respective initial values, the one ormore state variables associated with a communication window of acommunication session; receiving an RLC control message including anindication of a set of one or more values associated with the one ormore state variables, at least one value of the set of one or morevalues is different than at least one respective value of the set of oneor more initial values; and synchronizing the communication window withthe communication session based on setting the one or more statevariables to the set of one or more values. In some examples, thetechniques in the first aspect may be implemented in a method orprocess. In some other examples, the techniques of the first aspect maybe implemented in a wireless communication device such as a UE or acomponent of a UE. In some examples, the wireless communication devicemay include at least one processing unit or system (which may include anapplication processor, a modem or other components) and at least onememory device coupled to the processing unit. The processing unit may beconfigured to perform operations described herein with respect to thewireless communication device. In some examples, the memory deviceincludes a non-transitory computer-readable medium having program codestored thereon that, when executed by the processing unit, is configuredto cause the wireless communication device to perform the operationsdescribed herein.

In a second aspect, in combination with the first aspect, the techniquesfurther include receiving or transmitting a packet associated with thecommunication session within the communication window based on thesynchronizing.

In a third aspect, in combination with the first aspect or the secondaspect, the RLC entity includes an RLC AM entity.

In a fourth aspect, in combination with one or more of the first aspectthrough the third aspect, the communication session includes a unicastcommunication session, a multicast communication session, or a broadcastcommunication.

In a fifth aspect, in combination with the fourth aspect, thecommunication session includes the multicast communication session.

In a sixth aspect, in combination with one or more of the first aspectthrough the fifth aspect, the techniques further include configuring theRLC entity, where configuring the RLC entity includes setting the one ormore state variables to the set of one or more respective initialvalues.

In a seventh aspect, in combination with the sixth aspect, the set ofone or more respective initial values is based on a standard.

In an eighth aspect, in combination with the sixth aspect or the seventhaspect, at least one value of the set of one or more respective initialvalues is zero.

In a ninth aspect, in combination with one or more of the sixth aspectthrough the eighth aspect, the techniques further include initiatingestablishment of the communication session after completion ofconfiguring the RLC entity.

In a tenth aspect, in combination with one or more of the sixth aspectthrough the ninth aspect, the techniques further include joining anongoing multicast data session corresponding to the communicationsession.

In an eleventh aspect, in combination with one or more of the sixthaspect through the tenth aspect, the RLC control message is included inan RLC PDU received next in time after completion of configuring the RLCentity.

In a twelfth aspect, in combination with one or more of the first aspectthrough the fifth aspect, the techniques further include configuring theRLC entity, after configuring the RLC entity, performing a handoveroperation to a target cell, and re-establishing the RLC entity based oncompletion of the handover operation to the target cell, the RLC controlmessage being received after the RLC entity is re-established.

In a thirteenth aspect, in combination with the twelfth aspect, the RLCcontrol message includes a synchronization PDU that includes theindication.

In a fourteenth aspect, in combination with the twelfth aspect or thethirteenth aspect, the RLC control message is included in an RLC PDUthat includes an assigned RLC SN.

In a fifteenth aspect, in combination with one or more of the firstaspect through the fourteenth aspect, setting the one or more statevariables based on the indication includes adjusting the one or morestate variables from the set of one or more respective initial values toa first set of one or more respective values based on the indication.

In a sixteenth aspect, in combination with one or more of the firstaspect through the fifteenth aspect, the communication window includes aTx window, an Rx window, or a combination thereof.

In a seventeenth aspect, in combination with one or more of the firstaspect through the sixteenth aspect, the one or more state variablesinclude a window size of the communication window, a lower edge valuefor the communication window, an upper edge value for the communicationwindow, or a combination thereof.

In an eighteenth aspect, in combination with one or more of the firstaspect through the seventeenth aspect, the one or more state variablesinclude a window size and a lower edge value or an upper edge value.

In a nineteenth aspect, in combination with one or more of the firstaspect or the eighteenth aspect, the techniques further include settingthe one or more state variables based on the indication, and, after thesetting and during the communication session, receiving one or moresynchronization PDUs, each of the one or more received synchronizationPDUs including a respective indication of a corresponding update of theone or more state variables.

In a twentieth aspect, in combination with the nineteenth aspect, thetechniques further include updating, in response to receiving onesynchronization PDU of the one or more synchronization PDUs, the one ormore state variables based on the respective indication included in thereceived one synchronization PDU.

In a twenty-first aspect, in combination with the nineteenth aspectthrough the twentieth aspect, the one or more synchronization PDUsinclude multiple synchronization PDUs transmitted periodically.

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In atwenty-second aspect, techniques for enabling management of a statevariable a may include generating an RLC control message including anindication of a set of one or more values of one or more respectivestate variables associated with a communication window of acommunication session, the set of one or more values of the one or morestate variables enable synchronization of the communication window andare different from a set of one or more initial values of the one ormore respective state variables; and transmitting the RLC controlmessage to a UE. In some examples, the techniques in the first aspectmay be implemented in a method or process. In some other examples, thetechniques of the first aspect may be implemented in a wirelesscommunication device such as a base station or a component of a basestation. In some examples, the wireless communication device may includeat least one processing unit or system (which may include an applicationprocessor, a modem or other components) and at least one memory devicecoupled to the processing unit. The processing unit may be configured toperform operations described herein with respect to the wirelesscommunication device. In some examples, the memory device includes anon-transitory computer-readable medium having program code storedthereon that, when executed by the processing unit, is configured tocause the wireless communication device to perform the operationsdescribed herein.

In a twenty-third aspect, in combination with the twenty-second aspect,the RLC control messages is associated with an RLC entity of the UE.

In a twenty-fourth aspect, in combination with the twenty-second aspector the twenty-third aspect, the RLC entity includes an RLC AM entity.

In a twenty-sixth aspect, in combination with one or more of thetwenty-second aspect through the twenty-fifth aspect, the communicationsession includes a unicast communication session, a multicastcommunication session, or a broadcast communication.

In a twenty-seventh aspect, in combination with one or more of thetwenty-second aspect through the twenty-sixth aspect, the communicationwindow includes a Tx window, an Rx window, or a combination thereof.

In a twenty-eighth aspect, in combination with one or more of thetwenty-second aspect through the twenty-seventh aspect, the one or morestate variables include a window size of the communication window, alower edge value for the communication window, an upper edge value forthe communication window, or a combination thereof.

In a twenty-ninth aspect, in combination with one or more of thetwenty-second aspect through the twenty-seventh aspect, the techniquesfurther include, after transmitting the RLC control message,transmitting or receiving a packet associated with the communicationsession.

In a thirtieth aspect, in combination with one or more of thetwenty-second aspect through the twenty-seventh aspect, the techniquesfurther include determining whether the UE joined the communicationsession or completed a handover operation, wherein the RLC controlmessage is transmitted to the UE based on a determine that the UE joinedthe communication session or completed the handover operation.

In a thirty-first aspect, in combination with the thirtieth aspect, theRLC control message is transmitted to the UE independent of an RLC SNassociated with the communication session.

In a thirty-second aspect, in combination with one or more of thetwenty-second aspect through the twenty-seventh aspect, the techniquesfurther include generating one or more synchronization PDUs, each of theone or more synchronization PDUs including a respective indication of acorresponding update of the one or more state variables, andtransmitting the one or more synchronization PDUs.

In a thirty-third aspect, in combination with the thirty-second aspect,the one or more synchronization PDUs include multiple synchronizationPDUs transmitted periodically.

In a thirty-fourth aspect, in combination with the thirty-second aspector the thirty-third aspect, each synchronization PDU of the one or moresynchronization PDUs is included in a respective RLC data PDU thatincludes an RLC SN assigned based on the communication session.

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In a thirty-fifthaspect, techniques for enabling management of a state variable mayinclude initializing one or more state variables to a set of one or morerespective initial values, the one or more state variables associatedwith a communication window of a communication session; receiving acontrol message including an indication of a set of one or more valuesassociated with the one or more state variables, at least one value ofthe set of one or more values being different than at least onerespective value of the set of one or more initial values; synchronizingthe communication window with the communication session based on settingthe one or more state variables to the set of one or more values; andreceiving or transmitting a packet associated with the communicationsession within the communication window based on the synchronizing. Insome examples, the techniques in the thirty-fifth aspect may beimplemented in a method or process. In some other examples, thetechniques of the thirty-fifth aspect may be implemented in a wirelesscommunication device such as a UE or a component of a UE. In someexamples, the wireless communication device may include at least oneprocessing unit or system (which may include an application processor, amodem or other components) and at least one memory device coupled to theprocessing unit. The processing unit may be configured to performoperations described herein with respect to the wireless communicationdevice. In some examples, the memory device includes a non-transitorycomputer-readable medium having program code stored thereon that, whenexecuted by the processing unit, is configured to cause the wirelesscommunication device to perform the operations described herein.

In a thirty-sixth aspect, in combination with the thirty-fifth aspect,the communication session includes a unicast communication session, amulticast communication session, or a broadcast communication.

In a thirty-seventh aspect, in combination with the thirty-sixth aspect,the communication session includes the multicast communication session.

In a thirty-eighth aspect, in combination with one or more of thethirty-fifth aspect through the thirty-seventh aspect, the one or morestate variables are associated with an RLC entity and the controlmessage includes an RLC control message.

In a thirty-ninth aspect, in combination with the thirty-eighth aspect,the RLC entity includes an RLC AM entity or an RLC UM entity.

In a fortieth aspect, in combination with the thirty-eighth aspect orthe thirty-ninth aspect, the techniques further include configuring theRLC entity, wherein configuring the RLC entity includes setting the oneor more state variables to the set of one or more respective initialvalues.

In a forty-first aspect, in combination with the fortieth aspect, theset of one or more respective initial values is based on a standard.

In a forty-second aspect, in combination with the fortieth aspect or theforty-first aspect, at least one value of the set of one or morerespective initial values is zero.

In a forty-third aspect, in combination with one or more of the fortiethaspect through the forty-second aspect, the techniques further includeinitiating establishment of the communication session after completionof configuring the RLC entity.

In a forty-fourth aspect, in combination with one or more of thefortieth aspect through the forty-third aspect, the techniques furtherinclude joining an ongoing multicast data session corresponding to thecommunication session.

In a forty-fifth aspect, in combination with one or more of the fortiethaspect through the forty-fourth aspect, the RLC control message isincluded in an RLC protocol data unit (PDU) received next in time aftercompletion of configuring the RLC entity.

In a forty-sixth aspect, in combination with the thirty-eighth aspect orthe thirty-ninth aspect, the techniques further include configuring theRLC entity.

In a forty-seventh aspect, in combination with the forty-sixth aspect,the techniques further include, after configuring the RLC entity,performing a handover operation to a target cell.

In a forty-eighth aspect, in combination with the forty-seventh aspect,the techniques further include re-establishing the RLC entity based oncompletion of the handover operation to the target cell, the RLC controlmessage being received after the RLC entity is re-established.

In a forty-ninth aspect, in combination with the forty-eighth aspect,the RLC control message includes a synchronization PDU that includes theindication.

In a fiftieth aspect, in combination with the forty-eighth aspect or theforty-ninth aspect, the RLC control message is included in an RLC dataPDU that includes an assigned RLC SN.

In a fifty-first aspect, in combination with one or more of thethirty-fifth aspect through the thirty-seventh aspect, the one or morestate variables are associated with a PDCP entity and the controlmessage includes a PDCP control message.

In a fifty-second aspect, in combination with one or more of thethirty-fifth aspect through the thirty-seventh aspect, the techniquesfurther include receiving an RRC message that indicates the set of oneor more initial values.

In a fifty-third aspect, in combination with the fifty-first aspect orthe fifty-second aspect, the techniques further include configuring thePDCP entity, wherein configuring the PDCP entity includes setting theone or more state variables to the set of one or more respective initialvalues.

In a fifty-fourth aspect, in combination with the fifty-third aspect,the set of one or more respective initial values is based on a standard.

In a fifty-fifth aspect, in combination with the fifty-third aspect orthe fifty-fourth aspect, at least one value of the set of one or morerespective initial values is zero.

In a fifty-sixth aspect, in combination with one or more of thefifty-third aspect through the fifty-fifth aspect, the techniquesfurther include initiating establishment of the communication sessionafter completion of configuring the PDCP entity.

In a fifty-seventh aspect, in combination with one or more of thefifty-third aspect through the fifty-sixth aspect, the techniquesfurther include joining an ongoing multicast data session correspondingto the communication session.

In a fifty-eighth aspect, in combination with one or more of thefifty-third aspect through the fifty-seventh aspect, the PDCP controlmessage is included in a PDCP PDU received next in time after completionof configuring the PDCP entity.

In a fifty-ninth aspect, in combination with the fifty-first aspect, thetechniques further include configuring the PDCP entity.

In a sixtieth aspect, in combination with the fifty-ninth aspect, thetechniques further include, after configuring the PDCP entity,performing a handover operation to a target cell.

In a sixty-first aspect, in combination with the sixtieth aspect, thetechniques further include re-establishing the PDCP entity based oncompletion of the handover operation to the target cell, the PDCPcontrol message being received after the PDCP entity is re-established.

In a sixty-second aspect, in combination with the forty-ninth aspect,the PDCP control message includes a synchronization PDU that includesthe indication.

In a sixty-third aspect, in combination with one or more of thethirty-fifth aspect through the sixty-second aspect, setting the one ormore state variables based on the indication includes adjusting the oneor more state variables from the set of one or more respective initialvalues to a first set of one or more respective values based on theindication.

In a sixty-fourth aspect, in combination with one or more of thethirty-fifth aspect through the sixty-third aspect, the communicationwindow includes a Tx window, an Rx window, or a combination thereof.

In a sixty-fifth aspect, in combination with one or more of thethirty-fifth aspect through the sixty-fourth aspect, the one or morestate variables include a window size of the communication window, alower edge value for the communication window, an upper edge value forthe communication window, or a combination thereof.

In a sixty-sixth aspect, in combination with one or more of thethirty-fifth aspect through the sixty-fifth aspect, the one or morestate variables include a window size and a lower edge value or an upperedge value.

In a sixty-seventh aspect, in combination with one or more of thethirty-fifth aspect through the sixty-sixth aspect, the techniquesfurther include setting the one or more state variables based on theindication.

In a sixty-eighth aspect, in combination with the sixty-seventh aspect,the techniques further include, after the setting and during thecommunication session, receiving one or more synchronization PDUs, eachof the one or more received synchronization PDUs including a respectiveindication of a corresponding update of the one or more state variables.

In a sixty-ninth aspect, in combination with the sixty-eighth aspect,the techniques further include updating, in response to receiving onesynchronization PDU of the one or more synchronization PDUs, the one ormore state variables based on the respective indication included in thereceived one synchronization PDU.

In a seventieth aspect, in combination with the sixty-sixth aspect orthe sixty eighth aspect, the one or more synchronization PDUs includemultiple synchronization PDUs transmitted periodically.

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In aseventy-first aspect, techniques for enabling management of a statevariable a may include generating a control message including anindication of a set of one or more values of one or more respectivestate variables associated with a communication window of acommunication session, the set of one or more values of the one or morestate variables enable synchronization of the communication window andare different from a set of one or more initial values of the one ormore respective state variables; and transmitting the control message toa UE. In some examples, the techniques in the seventy-first aspect maybe implemented in a method or process. In some other examples, thetechniques of the seventy-first aspect may be implemented in a wirelesscommunication device such as a base station or a component of a basestation. In some examples, the wireless communication device may includeat least one processing unit or system (which may include an applicationprocessor, a modem or other components) and at least one memory devicecoupled to the processing unit. The processing unit may be configured toperform operations described herein with respect to the wirelesscommunication device. In some examples, the memory device includes anon-transitory computer-readable medium having program code storedthereon that, when executed by the processing unit, is configured tocause the wireless communication device to perform the operationsdescribed herein.

In a seventy-second aspect, in combination with the seventy-firstaspect, the control message includes an RLC control messages isassociated with an RLC entity of the UE.

In a seventy-third aspect, in combination with the seventy-secondaspect, the RLC entity includes an RLC AM entity or an RLC UM entity.

In a seventy-fourth aspect, in combination with the seventy-second orthe seventy-third aspect, the techniques further include, aftertransmitting the RLC control message, transmitting or receiving a packetassociated with the communication session.

In a seventy-fifth aspect, in combination with one or more of theseventy-second aspect through the seventy-fourth aspect, the techniquesfurther include determining whether the UE joined the communicationsession or completed a handover operation, wherein the RLC controlmessage is transmitted to the UE based on a determination that the UEjoined the communication session or completed the handover operation.

In a seventy-sixth aspect, in combination with the seventy-fifth aspect,the RLC control message is transmitted to the UE independent of an RLCSN associated with the communication session.

In a seventy-seventh aspect, in combination with one or more of theseventy-first aspect through the seventy-sixth aspect, the techniquesfurther include generating one or more synchronization PDUs, each of theone or more synchronization PDUs including a respective indication of acorresponding update of the one or more state variables.

In a seventy-eighth aspect, in combination with the seventy-seventhaspect, the techniques further include initiating transmission of ortransmitting the one or more synchronization PDUs.

In a seventy-ninth aspect, in combination with the seventy-eighthaspect, the one or more synchronization PDUs include multiplesynchronization PDUs transmitted periodically.

In an eightieth aspect, in combination with the seventy-eighth aspect orthe seventy-ninth, each synchronization PDU of the one or moresynchronization PDUs is included in a respective RLC data PDU thatincludes an RLC SN assigned based on the communication session.

In an eighty-first aspect, in combination with the seventy-first aspect,the control message includes a PDCP control messages is associated withan RLC entity of the UE.

In an eighty-second aspect, in combination with the eighty-first aspect,the techniques further include determining whether the UE joined thecommunication session or completed a handover operation. In someimplementations of the eighty-second aspect, the PDCP control message istransmitted to the UE based on a determination that the UE joined thecommunication session or completed the handover operation.

In an eighty-third aspect, in combination with the eighty-first aspector the eighty-second aspect, the techniques further include generatingone or more synchronization PDUs, each of the one or moresynchronization PDUs including a respective indication of acorresponding update of the one or more state variables.

In an eighty-fourth aspect, in combination with the eighty-third aspect,the techniques further include initiating transmission of ortransmitting the one or more synchronization PDUs.

In an eighty-fifth aspect, in combination with the eighty-fourth aspect,the one or more synchronization PDUs include multiple synchronizationPDUs transmitted periodically or each synchronization PDU of the one ormore synchronization PDUs is included in a respective PDCP data PDU

In an eighty-sixth aspect, in combination with the eighty-fourth aspect,at least one synchronization PDU of the one or more synchronization PDUsis transmitted based on a determination that the UE transitioned from aphysical layer being out-of-sync to a physical layer being in-sync, adetermination that a number of packet retransmissions is greater than orequal to a threshold, a network load balancing or retransmission policy,or a determination that a PDCP level is lost.

In an eighty-seventh aspect, in combination with one or more of theseventy-first aspect through the eighty-sixth aspect, the communicationsession includes a unicast communication session, a multicastcommunication session, or a broadcast communication.

In an eighty-eighth aspect, in combination with one or more of theseventy-first aspect through the eighty-seventh aspect, thecommunication window includes a Tx window, an Rx window, or acombination thereof.

In an eighty-ninth aspect, in combination with one or more of theseventy-first aspect through the eighty-eighth aspect, the one or morestate variables include a window size of the communication window, alower edge value for the communication window, an upper edge value forthe communication window, or a combination thereof.

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In a ninetiethaspect, techniques for enabling management of a state variable a mayinclude initializing a set of state variables to a first set of initialvalues, respectively, the set of state variables being associated withsynchronization of a communication window of a communication session;receiving a control message including an indication of a second set ofcurrent values associated with respective state variables of the set ofstate variables, at least one of the current values being different thana respective one of the initial values; setting the set of statevariables to the second set of current values to synchronize thecommunication window with the communication session; and receiving ortransmitting a packet associated with the communication session withinthe synchronized communication window. In some examples, the techniquesin the ninetieth aspect may be implemented in a method or process. Insome other examples, the techniques of the ninetieth aspect may beimplemented in a wireless communication device such as a UE or acomponent of a UE. In some examples, the wireless communication devicemay include at least one processing unit or system (which may include anapplication processor, a modem or other components) and at least onememory device coupled to the processing unit. The processing unit may beconfigured to perform operations described herein with respect to thewireless communication device. In some examples, the memory deviceincludes a non-transitory computer-readable medium having program codestored thereon that, when executed by the processing unit, is configuredto cause the wireless communication device to perform the operationsdescribed herein.

In a ninety-first aspect, in combination with the ninetieth aspect, thecommunication session includes a unicast communication session, amulticast communication session, or a broadcast communication.

In a ninety-second aspect, in combination with the ninety-first aspect,the communication session includes the multicast communication session.

In a ninety-third aspect, in combination with the ninetieth aspect, theset of state variables is associated with an RLC entity that includes anRLC AM entity or an RLC UM entity.

In a ninety-fourth aspect, in combination with the ninety-third aspect,the techniques further include configuring the RLC entity, whereinconfiguring the RLC entity includes setting the set of state variablesto the first set of respective initial values.

In a ninety-fifth aspect, in combination with the ninety-fourth aspect,the first set of respective initial values is based on a standard.

In a ninety-sixth aspect, in combination with the ninety-fourth aspect,at least one value of the first set of respective initial values iszero.

In a ninety-seventh aspect, in combination with the ninety-fourthaspect, the techniques further include initiating establishment of thecommunication session after completion of configuring the RLC entity.

In a ninety-eighth aspect, in combination with the ninety-fourth aspect,the techniques further include joining an ongoing multicast data sessioncorresponding to the communication session.

In a ninety-ninth aspect, in combination with the ninety-fourth aspect,the RLC control message is included in an RLC PDU received next in timeafter completion of configuring the RLC entity.

In a one hundredth aspect, in combination with the ninety-third aspect,the techniques further include configuring the RLC entity.

In a one hundredth and first aspect, in combination with the onehundredth aspect, the techniques further include, after configuring theRLC entity, performing a handover operation to a target cell.

In a one hundredth and second aspect, in combination with the onehundredth and first aspect, the techniques further includere-establishing the RLC entity based on completion of the handoveroperation to the target cell, the RLC control message being receivedafter the RLC entity is re-established.

In a one hundredth and third aspect, in combination with the onehundredth and second aspect, the RLC control message includes asynchronization PDU that includes the indication.

In a one hundredth and fourth aspect, in combination with the onehundredth and second aspect, the RLC control message is included in anRLC data PDU that includes an assigned RLC SN.

In a one hundredth and fifth aspect, in combination with the ninetiethaspect, 68. setting the set of state variables based on the indicationincludes adjusting the set of state variables from the first set ofrespective initial values to the second set of current values.

In a one hundredth and sixth aspect, in combination with the ninetiethaspect, the communication window includes a Tx window, an Rx window, ora combination thereof.

In a one hundredth and seventh aspect, in combination with the ninetiethaspect, the set of state variables include a window size of thecommunication window, a lower edge value for the communication window,an upper edge value for the communication window, or a combinationthereof.

In a one hundredth and eighth aspect, in combination with the ninetiethaspect, the set of state variables include a window size and a loweredge value or an upper edge value.

In a one hundredth and ninth aspect, in combination with the ninetiethaspect, the techniques further include setting the set of statevariables based on the indication.

In a one hundredth and tenth aspect, in combination with the onehundredth and ninth aspect, the techniques further include, after thesetting and during the communication session, receiving one or moresynchronization PDUs, each of the one or more received synchronizationPDUs including a respective indication of a corresponding update of theset of state variables.

In a one hundredth and eleventh aspect, in combination with theninetieth aspect, the techniques further include updating, in responseto receiving one synchronization PDU of the one or more synchronizationPDUs, the set of state variables based on the respective indicationincluded in the received one synchronization PDU.

In a one hundredth and twelfth aspect, in combination with the ninetiethaspect, the one or more synchronization PDUs include multiplesynchronization PDUs transmitted periodically.

In a one hundredth and thirteenth aspect, in combination with theninetieth aspect, the set of state variables are associated with a PDCPentity and the control message includes a PDCP control message.

In a one hundredth and fourteenth aspect, in combination with theninetieth aspect, the techniques further include receiving an RRCmessage that indicates the first set of initial values.

In a one hundredth and fifteenth aspect, in combination with the onehundredth and thirteenth aspect, the techniques further includeconfiguring the PDCP entity, wherein configuring the PDCP entityincludes setting the set of state variables to the first set ofrespective initial values.

In a one hundredth and sixteenth aspect, in combination with the onehundredth and fifteenth aspect, the first set of respective initialvalues is based on a standard.

In a one hundredth and seventeenth aspect, in combination with the onehundredth and fifteenth aspect, at least one value of the first set ofrespective initial values is zero.

In a one hundredth and eighteenth aspect, in combination with the onehundredth and fifteenth aspect, the techniques further includeinitiating establishment of the communication session after completionof configuring the PDCP entity.

In a one hundredth and nineteenth aspect, in combination with the onehundredth and fifteenth aspect, the techniques further include joiningan ongoing multicast data session corresponding to the communicationsession.

In a one hundredth and twentieth aspect, in combination with the onehundredth and fifteenth aspect, the PDCP control message is included ina PDCP PDU received next in time after completion of configuring thePDCP entity.

In a one hundredth and twenty-first aspect, in combination with theninetieth aspect, the techniques further include configuring the PDCPentity.

In a one hundredth and twenty-second aspect, in combination with the onehundredth and twenty-first aspect, the techniques further include, afterconfiguring the PDCP entity, performing a handover operation to a targetcell.

In a one hundredth and twenty-third aspect, in combination with the onehundredth and twenty-second aspect, the techniques further includere-establishing the PDCP entity based on completion of the handoveroperation to the target cell, the PDCP control message being receivedafter the PDCP entity is re-established.

In a one hundredth and twenty-fourth aspect, in combination with the onehundredth and twenty-third aspect, the PDCP control message includes asynchronization PDU that includes the indication.

In some aspects, techniques for enabling management of a state variablemay include additional aspects, such as any single aspect or anycombination of aspects described below or in connection with one or moreother processes or devices described elsewhere herein. In a onehundredth and twenty-fifth aspect, techniques for enabling management ofa state variable a may include generating a control message including anindication of a set of values of a set of state variables associatedwith a communication window of a communication session, the set ofvalues enable synchronization of the communication window and aredifferent from a set of initial values of the set of state variables;and transmitting the control message to a UE. In some examples, thetechniques in the one hundredth and twenty-fifth aspect may beimplemented in a method or process. In some other examples, thetechniques of the one hundredth and twenty-fifth aspect may beimplemented in a wireless communication device such as a base station ora component of a base station. In some examples, the wirelesscommunication device may include at least one processing unit or system(which may include an application processor, a modem or othercomponents) and at least one memory device coupled to the processingunit. The processing unit may be configured to perform operationsdescribed herein with respect to the wireless communication device. Insome examples, the memory device includes a non-transitorycomputer-readable medium having program code stored thereon that, whenexecuted by the processing unit, is configured to cause the wirelesscommunication device to perform the operations described herein.

In a one hundredth and twenty-sixth aspect, in combination with the onehundredth and twenty-fifth aspect, the control messages is associatedwith an RLC entity of the UE.

In a one hundredth and twenty-seventh aspect, in combination with theone hundredth and twenty-sixth aspect, the RLC entity includes an RLC AMentity or an RLC UM entity.

In a one hundredth and twenty-eighth aspect, in combination with the onehundredth and twenty-fifth aspect, the communication session includes aunicast communication session, a multicast communication session, or abroadcast communication.

In a one hundredth and twenty-ninth aspect, in combination with the onehundredth and twenty-fifth aspect, the communication window includes aTx window, an Rx window, or a combination thereof.

In a one hundredth and thirtieth aspect, in combination with the onehundredth and twenty-fifth aspect, the set of state variables include awindow size of the communication window, a lower edge value for thecommunication window, an upper edge value for the communication window,or a combination thereof.

In a one hundredth and thirty-first aspect, in combination with the onehundredth and twenty-sixth aspect, the techniques further includetransmitting an RRC message that indicates the set of initial values,or, after transmitting the control message, transmitting or receiving apacket associated with the communication session.

In a one hundredth and thirty-second aspect, in combination with the onehundredth and twenty-sixth aspect, the techniques further includedetermining whether the UE joined the communication session or completeda handover operation, wherein the control message is transmitted to theUE based on a determine that the UE joined the communication session orcompleted the handover operation.

In a one hundredth and thirty-third aspect, in combination with the onehundredth and thirty-second aspect, the RLC control message istransmitted to the UE independent of an RLC SN associated with thecommunication session.

In a one hundredth and thirty-fourth aspect, in combination with the onehundredth and twenty-fifth aspect, the techniques further includegenerating one or more synchronization PDUs, each of the one or moresynchronization PDUs including a respective indication of acorresponding update of the set of state variables.

In a one hundredth and thirty-fifth aspect, in combination with the onehundredth and thirty-fourth aspect, the techniques further includeinitiating transmission of or transmitting the one or moresynchronization PDUs.

In a one hundredth and thirty-sixth aspect, in combination with the onehundredth and thirty-fifth aspect, the one or more synchronization PDUsinclude multiple synchronization PDUs transmitted periodically.

In a one hundredth and thirty-seventh aspect, in combination with theone hundredth and thirty-fifth aspect, each synchronization PDU of theone or more synchronization PDUs is included in a respective RLC dataPDU that includes an RLC SN assigned based on the communication session.

In a one hundredth and thirty-eighth aspect, in combination with the onehundredth and twenty-fifth aspect, the control message includes a PDCPcontrol message.

In a one hundredth and thirty-ninth aspect, in combination with the onehundredth and thirty-eighth aspect, the techniques further includedetermining whether the UE joined the communication session or completeda handover operation, wherein the PDCP control message is transmitted tothe UE based on a determination that the UE joined the communicationsession or completed the handover operation.

In a one hundredth and fortieth aspect, in combination with the onehundredth and thirty-eighth aspect, the techniques further includegenerating one or more synchronization PDUs, each of the one or moresynchronization PDUs including a respective indication of acorresponding update of the set of state variables.

In a one hundredth and forty-first aspect, in combination with the onehundredth and fortieth aspect, the techniques further include initiatingtransmission of or transmitting the one or more synchronization PDUs.

In a one hundredth and forty-second aspect, in combination with the onehundredth and forty-first aspect, the one or more synchronization PDUsinclude multiple synchronization PDUs transmitted periodically.

In a one hundredth and forty-third aspect, in combination with the onehundredth and forty-first aspect, each synchronization PDU of the one ormore synchronization PDUs is included in a respective PDCP data PDU.

In a one hundredth and forty-fourth aspect, in combination with the onehundredth and forty-first aspect, at least one synchronization PDU ofthe one or more synchronization PDUs is transmitted based on adetermination that the UE transitioned from a physical layer beingout-of-sync to a physical layer being in-sync, a determination that anumber of packet retransmissions is greater than or equal to athreshold, a network load balancing or retransmission policy, or adetermination that a PDCP level is lost.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Components, the functional blocks, and the modules described herein withrespect to FIGS. 1-8 include processors, electronics devices, hardwaredevices, electronics components, logical circuits, memories, softwarecodes, firmware codes, among other examples, or any combination thereof.In addition, features discussed herein may be implemented viaspecialized processor circuitry, via executable instructions, orcombinations thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure. Skilled artisans will also readilyrecognize that the order or combination of components, methods, orinteractions that are described herein are merely examples and that thecomponents, methods, or interactions of the various aspects of thepresent disclosure may be combined or performed in ways other than thoseillustrated and described herein.

The various illustrative logics, logical blocks, modules, circuits andalgorithm processes described in connection with the implementationsdisclosed herein may be implemented as electronic hardware, computersoftware, or combinations of both. The interchangeability of hardwareand software has been described generally, in terms of functionality,and illustrated in the various illustrative components, blocks, modules,circuits and processes described above. Whether such functionality isimplemented in hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

The hardware and data processing apparatus used to implement the variousillustrative logics, logical blocks, modules and circuits described inconnection with the aspects disclosed herein may be implemented orperformed with a general purpose single- or multi-chip processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, or, any conventional processor, controller,microcontroller, or state machine. In some implementations, a processormay be implemented as a combination of computing devices, such as acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. In some implementations,particular processes and methods may be performed by circuitry that isspecific to a given function.

In one or more aspects, the functions described may be implemented inhardware, digital electronic circuitry, computer software, firmware,including the structures disclosed in this specification and theirstructural equivalents thereof, or in any combination thereof.Implementations of the subject matter described in this specificationalso can be implemented as one or more computer programs, that is one ormore modules of computer program instructions, encoded on a computerstorage media for execution by, or to control the operation of, dataprocessing apparatus.

If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. The processes of a method or algorithmdisclosed herein may be implemented in a processor-executable softwaremodule which may reside on a computer-readable medium. Computer-readablemedia includes both computer storage media and communication mediaincluding any medium that can be enabled to transfer a computer programfrom one place to another. A storage media may be any available mediathat may be accessed by a computer. By way of example, and notlimitation, such computer-readable media may include RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that may be used to storedesired program code in the form of instructions or data structures andthat may be accessed by a computer. Also, any connection can be properlytermed a computer-readable medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk, and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes andinstructions on a machine readable medium and computer-readable medium,which may be incorporated into a computer program product.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to some otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Additionally, a person having ordinary skill in the art will readilyappreciate, the terms “upper” and “lower” are sometimes used for ease ofdescribing the figures, and indicate relative positions corresponding tothe orientation of the figure on a properly oriented page, and may notreflect the proper orientation of any device as implemented.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, some other implementations are within the scope of thefollowing claims. In some cases, the actions recited in the claims canbe performed in a different order and still achieve desirable results.

As used herein, including in the claims, the term “or,” when used in alist of two or more items, means that any one of the listed items can beemployed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, or C, the composition can contain A alone; Balone; C alone; A and B in combination; A and C in combination; B and Cin combination; or A, B, and C in combination. Also, as used herein,including in the claims, “or” as used in a list of items prefaced by “atleast one of” indicates a disjunctive list such that, for example, alist of “at least one of A, B, or C” means A or B or C or AB or AC or BCor ABC (that is A and B and C) or any of these in any combinationthereof. The term “substantially” is defined as largely but notnecessarily wholly what is specified (and includes what is specified;for example, substantially 90 degrees includes 90 degrees andsubstantially parallel includes parallel), as understood by a person ofordinary skill in the art. In any disclosed implementations, the term“substantially” may be substituted with “within [a percentage] of” whatis specified, where the percentage includes 0.1, 1, 5, or 10 percent.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. A method for wireless communication performed by a user equipment(UE), the method comprising: receiving a control message generated at anetwork entity, the control message indicating a value of a statevariable maintained by the network entity, the state variable associatedwith a communication window of a communication session established withthe network entity; setting, based on the control message, the statevariable to the value from an initial value set during an initializationoperation; and receiving data associated with the communication sessionwithin the communication window based on the value of the statevariable.
 2. The method of claim 1, wherein the control message includesa packet data convergence protocol (PDCP) control message.
 3. The methodof claim 1, further comprising: synchronizing the communication windowwith the network entity based on setting the state variable to thevalue.
 4. The method of claim 1, wherein the state variable includesRX_NEXT, RX_DELIV, or both.
 5. The method of claim 1, furthercomprising: initializing the state variable to the initial valueselected from among a plurality of possible initial values.
 6. Themethod of claim 1, wherein the value is distinct from the initial value.7. The method of claim 1, wherein the communication session includes aunicast communication session, a multicast communication session, or abroadcast communication session.
 8. The method of claim 1, wherein thecommunication session includes a multicast communication session, themethod further comprising: joining the communication session, whereinreceiving the control message is in response to joining thecommunication session.
 9. The method of claim 1, wherein the controlmessage is included in a radio resource control (RRC) message.
 10. Themethod of claim 1, wherein the data includes packet data convergenceprotocol (PDCP) data.
 11. The method of claim 1, wherein receiving thecontrol message includes receiving the control message as part of ahandover operation between a second network entity and the networkentity.
 12. An apparatus for wireless communication, the apparatuscomprising: a processing system that includes one or more processors andone or more memories coupled with the one or more processors, theprocessing system configured to: receive a control message generated ata network entity, the control message indicating a value of a statevariable maintained by the network entity, the state variable associatedwith a communication window of a communication session established withthe network entity; set, based on the control message, the statevariable to the value from an initial value set during an initializationoperation; and receive data associated with the communication sessionwithin the communication window based on the value of the statevariable.
 13. The apparatus of claim 12, wherein the control messageincludes a packet data convergence protocol (PDCP) control message. 14.The apparatus of claim 12, wherein the processing system is furtherconfigured to: synchronize the communication window with the networkentity based on setting the state variable to the value.
 15. Theapparatus of claim 12, wherein the state variable includes RX_NEXT,RX_DELIV, or both.
 16. The apparatus of claim 12, wherein the processingsystem is further configured to: initialize the state variable to theinitial value selected from among a plurality of possible initialvalues.
 17. The apparatus of claim 12, wherein the value is distinctfrom the initial value.
 18. The apparatus of claim 12, wherein thecommunication session includes a unicast communication session, amulticast communication session, or a broadcast communication session.19. The apparatus of claim 12, wherein the communication sessionincludes a multicast communication session, and wherein the processingsystem is further configured to: join the communication session,wherein, to receive the control message, the processing system isconfigured to receive the control message in response to joining thecommunication session.
 20. The apparatus of claim 12, wherein thecontrol message is included in a radio resource control (RRC) message.21. The apparatus of claim 12, wherein the data includes packet dataconvergence protocol (PDCP) data.
 22. The apparatus of claim 12,wherein, to receive the control message, the processing system isconfigured to: receive the control message as part of a handoveroperation between a second network entity and the network entity.
 23. Amethod of wireless communication performed by a network entity, themethod comprising: generating a control message that indicates a valueof a state variable maintained by the network entity, the state variableassociated with a communication window of a communication sessionestablished with a user equipment (UE); transmitting the control messageto the UE; and transmitting, to the UE, data associated with thecommunication session within the communication window based on the valueof the state variable.
 24. The method of claim 23, wherein the controlmessage includes a packet data convergence protocol (PDCP) controlmessage, and wherein the control message is included in a radio resourcecontrol (RRC) message.
 25. The method of claim 23, wherein the value isdistinct from an initial value of a corresponding instantiation of thestate variable stored in a memory of the UE.
 26. The method of claim 1,wherein transmitting the control message to the UE includes transmittingthe control message to the UE in response to joining the communicationsession with the UE.
 27. An apparatus for wireless communication, theapparatus comprising: a processing system that includes one or moreprocessors and one or more memories coupled with the one or moreprocessors, the processing system configured to: generate a controlmessage that indicates a value of a state variable maintained in the oneor more memories, the state variable associated with a communicationwindow of a communication session established with a user equipment(UE); transmit the control message to the UE; and transmit, to the UE,data associated with the communication session within the communicationwindow based on the value of the state variable.
 28. The apparatus ofclaim 27, wherein the control message includes a packet data convergenceprotocol (PDCP) control message, and wherein the control message isincluded in a radio resource control (RRC) message.
 29. The apparatus ofclaim 27, wherein the value is distinct from an initial value of acorresponding instantiation of the state variable stored in the one ormore memories of the UE.
 30. The apparatus of claim 27, wherein, totransmit the control message, the processing system is configured totransmit the control message to the UE in response to joining thecommunication session with the UE.